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Zinsser included, had private income and it was not uncommon for professors to support their research from their own funds. There were far fewer scientists in Zinsser's day. They relied heavily on each other, utilizing openness as a means of repeating and verifying studies and results. Their good names and reputations were what they traded on. Consequently Dr. Zinsser's assertion that head lice transmitted typhus is one to be taken seriously. Not because typhus may or may not be a threat, but because studies with head lice and this disease shed light on the prevailing assumption that head lice are not capable of transmitting any disease.
As a victim of Mexican typhus and renowned as a world authority on the subject, Zinsser would never had made this statement without what he believed to be firm evidence. The search for substantiation of his assertion led to his papers in the Archives of the Harvard Countway Medical Library, where a great deal more was discovered than expected.
Zinsser was fascinating in ways far beyond his work with typhus.
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A poet in the tradition of his Harvard Medical School predecessor, Oliver Wendell Holmes, his nature deeply influenced his students. For example, Dr. John Enders, then an English major, casually sat in on one of Dr. Zinsser's lectures. Enders was so taken by one of Zinsser's lectures that he changed his major, studied in Zinsser's labs and ultimately won the Nobel Prize for his work on the polio virus. Zinsser's own achievements are equally impressive: after receiving his Masters degree and M. He received honorary degrees from five universities, including Columbia, Harvard and Yale.
The science that went into this achievement was performed over decades, in laboratories all over the world, and Zinsser -- who always shied away from publicity went out of his way to deprecate his own contributions. According to Dr. Jack Snyder, Zinsser's onetime associate and former Dean of the Harvard School of Public Health, Zinsser spent his last weeks in the laboratory searching feverishly for the exact place where an error committed by his lab technician might have gotten into the data.
This uncompromising commitment to the truth reaffirms convictions that Zinsser's passing observation that head lice could transmit typhus is one with which modern science must come to terms. The unambiguous assertion of such a man that head lice could transmit disease arose from his clear understanding of the research in this area.
In the French physician and bacteriologist Charles Nicolle, to whom Zinsser dedicated Rats, Lice and History , was awarded the Nobel Prize for Medicine for demonstrating that lice transmitted typhus. The citation made specific mention of "the successful transmission of exanthematous typhus fever to chimpanzees in the acute stages by the injection of a small amount of the body louse.
Wilson's standard Nobel Prize Winners notes, his discovery "involved no new principles. The louse that Nicolle implicated in typhus transmission was the body louse, for Nicolle had discovered that typhus patients ceased to be infectious after they had been admitted to hospitals, where they were washed, shaved and given clean clothing. It could only be the louse. Soon after the publication of this paper two American researchers for the U. Public Health and Marine-Hospital service investigated the possibilities of disease transmission by the head louse.
In their article, Joseph Goldberger and John F. Anderson demonstrated "the first evidence incriminating any insect other than the body louse as an intermediary in the transmission of typhus fever. In the German investigator H. Toepfer reported finding the typhus parasite in head lice of typhus patients. Hanser confirmed Toepfer's finding. The following year George Henry Falkner Nuttal, who has been called the "Father of Parasitology," summarized the role played by Pediculus humanus human lice , in the etiology of both typhus and relapsing fever.
He stated that "P. In a review paper Nicolle himself stated that "the head louse transmits typhus like the body louse. Jack Snyder, witnessed the human suffering of typhus on the medical front lines as far away as Egypt, and worked to develop improved methods for field isolation of the disease's causative agent, Rickettsia prowazekii. Snyder also worked beside Zinsser in the lab and later wrote in his chapter on Typhus in Viral and Rickettsial Infections of Man that "classic epidemic typhus is a disease which occurs as a natural infection of man, the human body louse--and the human head louse.
As recently as E. Murray and S. Torrey of the Harvard School of Public Health confirmed that head lice could be readily infected with virulent rickettsia by feeding upon infected animals. Despite the evidence provided by these and other studies, and despite Zinsser's statement in Rats, Lice and History, continuously in print since its publication in , the prevailing medical view today is that the ubiquitous head louse cannot transmit disease.
No trials were found in the nearly eight decades since Goldberger and Anderson's demonstration that refute or even challenge any of the earlier investigators' conclusions. Why, then has the head louse been exonerated? How has the medical community arrived at a view that so completely disregards repeatedly confirmed evidence of the head louse's ability to transmit serious disease?
Historically, the head louse has been perceived as incidental to the body louse. The most extensive research on lice was conducted when epidemic typhus threatened public health, a time when the body louse was far more prevalent than it is today. Although the head louse and body louse are closely related parasites, it was the body louse that served as the primary vector for typhus, and the epidemiologically unimportant head louse was rightfully assigned a low priority.
Eventually, typhus was brought under control and the incidence of body lice diminished through improved hygiene and sanitation. In the years that followed, research on lice behavior was largely restricted to studies for the development of pediculicide treatments. Murray and Torrey note "the greater prevalence of head lice over body lice is now becoming noticeable in traditional endemic typhus areas of Eastern and Southeastern Europe, such as Bosnia, Yugoslavia. Although these 'lice of affluence' chiefly involve head lice, we have to bear in mind that head lice are also able to become infected with, and transmit R.
This discussion earlier mentioned the reports of scientists whose research encompassed field work, clinical observation, and laboratory investigations of epidemic typhus. Each undoubtedly appreciated the importance of the body louse, but did not ignore the head louse and its capability to transmit the disease. Moreover, he knows — whenever he attacks a problem — that before he can advance toward his objec- tive, he must first recede into analysis of the individual elements that compose the complex systems with which he is occupied.
Such difficulties engender a habit of mind that has ham- pered us in the present undertaking. This is the difficulty faced by all the recent astro- nomical and physicist Khool of ponderers. We were first deflected into contemplation of the general methods of biographical writing; then arose the question why men occupied them- selves with the study of disease.
We thought we were through with preliminaries, when our literary friend dropped in again, and proceeded to scatter salt upon our enthusiasm. You might be right about the keyhole biographers and the pasteurized Rabelaisian school of Freudian critics, but is that any worse than the literary- scientific spinster movement? Read the Atlantic Monthly. Here in America we seem to expect a specialist to become a sort of Taylorized factory worker.
Why should a man look at the world through only one knot-hole? Biography is a job for an artist. Stick your head oat of your laboratory window and watch the world go by. But if you want to write, pull it in again and write for the Journal of Experimental Medicine. Is literature to be appraised only by those who have time to 'read after breakfast? The late war between humanists and antihumanists might have brought an answer — only both sides were so angry at each other and so ignorant of science that they neglected the main issue.
Babbitt, with his vast erudition, might have found a reply if he had lived. Toward the end, the small fry were keeping him too busy with his heels. Any- way, neither you nor I know enough to deal with it.
We approached the problem modestly by examining the opinions of others, and found that men far wiser than ourselves had failed to agree. But having ascended to these cold heights by laborious upward paths of reason, they sit down in their metaphysical tobog- gans and swish back into the warm and comfortable vales of theology. Whitehead penetrates more deeply beneath the mere morphology of the problem into its comparative anatomy and physiology. He includes, in the category of science, the biological branches and geology, and, more than that, he regards naturalistic art Leonardo as closely akin to science.
Incidentally, what a kick Aristotle would get out of Harvard! This separation on the basis of precision is utterly untenable. Science is not a whit more photographic than is art. Measurements and formulations are, even in the so-called exact — the physical — sciences, not much more than reasonably accurate approximations. Nature, as Goethe puts it, runs its course by such eternal and necessary principles that even the gods themselves cannot alter them.
The most that the scientist and the artist accomplish is new understanding of things that have always been. In both cases, the more generally applicable the observations, the greater is the science or art. The capacities of intelligence form a sort of spectrum which extends from what we may call an infra-emotional to an ultra- reason range. At the infra-emotional extreme lie the per- ceptions set in motion by music and by lyrical poetry. At the opposite end — that of pure reason — is placed the perceptional capacity for mathematics. Between the two there is a wide range of overlapping where art is scientific and science artistic.
Literature in the sense of prose may be taken to hold a middle ground, shading on the left into epic and narrative poetry, and on the right through psychology, biology, and so forth, toward mathematics. How many hidden heroes await only the example of a hero in a book, only a spark of life given off by his life in order to love, only a word from him in order to speak. In either case it ceases to be science or art. Critics like Cole- ridge or Sainte-Beuve needed to concern themselves only with style, beauty of diction, clarity of thought, intensity, sincerity, depth, and the qualities of taste and sensitive- ness which, while vague and subtle, were still within the scope of the underanged mind.
Art could be judged by any informed and intelligent critic without recourse to border- line psychiatry. On occasion these great men came close to the jumping-off place of uncomprchen- sibility. But in the main they achieved a great beauty by the very dusk and mist through which their thoughts, suflFerings, and joys were mysteriously, grotesquely, vaguely, but still effectively perceived. We make no plea for a return to Tennysonism or the Longfellow era, but had Sainte-Beuve been required to pass judg- ment on certain passages of T.
Eliot, the later Joyce, or Gertrude Stein, he would surely have gone into con- sultation with Charcot or Bernheim, a dilemma which our modern critics seem to admit — in their judgments of modern work — by their habitual appeal to Sigmund Freud. It is, of course, difficult, even in medical practice, to survey sharply the line between sanity and border- line derangements. But when the critic of a work of art needs psychiatric training, this fact alone would serve to throw suspicion on the artistic value of his subject. The real difficulty of applying our kind of spectroscopic analysis to much of the modern stuff lies in the fact that a good deal of it lacks the rationality of science without possessing the emotional appeal of art.
Take T. Eliot — who, in his prose, shows great clarity of thought and to whom no one will deny talent, originality, and, on occasion, great beauty. But in much of his poetry he plays, as has been aptly remarked, a guessing game with readers, whom he seems to appraise, apparently with some reason, as imbe- ciles.
See note 6a. Was she wise because she had a bad cold? It sounds like trivial prose. The thing as a whole symbolizes the Waste Land of modern disillusionment. Every now and then my monkeys get loose in the laboratory and achieve brilliant and bizarre effects by smashing bottles of coloured liquids against microscopes and Bunsen burners.
You can do the same thing with the workshops of art. But those men were making discoveries. Baudelaire was an organic chemist. He synthetized extraordinarily re- pulsive but new compounds. All of it to be as a wife has a cow, all of it to be as a wife has a cow, a love story. As to be all of it as to be a wife as a wife has a cow, a love story, all of it as to be all of it as a wife all of it as to be as a wife has a cow a love story. Bolony balloons; they have punctured my categorical imperative.
She was fifty, but she imagined she was a baby. Pease porridge in the pot. Eddy and P. Without Buffalo Bill, P. Barnum, or Mrs. Eddy, there might have been no Gertrude Stein, and Joyce might have continued to write distinguished prose. So one grand summer evening after a great morning and his good supper of gammon and spittish, having fiabelled his eyes, pilleoled his nostrils, vacticanated his ears. Skinner in the Atlantic Monthly for January 19 It would be too easy to dismiss the matter by assuming that they were mildly crazy.
More- over, the ability of the ones we have mentioned to return, at will, to the rational state excludes this. Valery says the poet is merely a sort of musician. Sometimes the critic goes much farther in his mysticism than the poets he writes about. I refer to Whitehead, and in disagreeing with him I feel much like a Neanderthal man attacking a mastodon with a bean-shooter. The sheer beauty of the shifting thoughts and feelings, and the musical beauty, — not only musical in sound, but in the harmony of images as well, — must arouse in the reader the same reaction, trans- mitted from the poet, which nature aroused in the poet himself.
The greatest poetry is communication and is clear. It may, through pure lyricism, progress sanely to the symbolism of Mallarme and his contemporaries, growing less and less intellectually clear — more and more dependent upon imagery and suggestion. Why, we must ask ourselves, have individuals of un- questionably great powers chosen to play with their minds like captive monkeys with their genitalia?
Lawrence had been a professional instead of an occasional painter. A painted Lady Chatterley — the most exquisite technique notwithstanding — would surely have been so completely out of drawing, with the lower parts so much larger than the upper, as to have been hardly recognizable as a human figure. This is the mild derange- ment that probably explains mediums.
Or 4 that it is barely possible they are yielding to the uncontrollable impulse to expose their own diseases, just as the physically sick like to tell about their operations or their chronic colitis. If they were commonplace people this exercise would attract only sympathetic attention.
These are formidable machines and one wishes the insulation had not burnt off the power lines. We distinctly exclude Hart Crane, whom we had occasion to know when we were working on typhus in Mexico. He was a man of great talent, appealing and tragic, for he was very sick in spirit. Thus in its primary sense, beauty is a quality which finds its exemplification in actual occasions.
Or, put it conversely, it is a quality in which such occasions can severally participate. You always know where you have them. You either leave them alone or approach them with cautious competence. Indeed, for all I know, perhaps they can. And there is no arsphenamin for the psychic treponema. Typhus is far less perilous. CHAPTER III Leading up to the definition of bacteria and other parasites y and digressing briefly into the question of the origin of life — a discussion without which the reader would be quite unprepared for what is to follow I In the history of the immense universe, that of our little planet is an isolated and probably unimportant episode.
On some older island in the immeasurable spaces, some other evolution may have produced beings so much wiser than ourselves that they can comprehend the origin of life. For there is no just reason to believe that we — transitional creatures in the upward progress of evolution — have reached the highest possibilities. The tragedy of man is that he has developed an intelligence eager to un- cover mysteries, but not strong enough to penetrate them. With minds but slightly evolved beyond those of our animal relations, we are tortured with precocious desires to pose questions which we are sometimes capable of ask- ing, but rarely are able to answer.
We have learned to dream of conquests of the forces about usj we investigate matter and the energy that moves it, the order that con- trols the worlds and the sun and the stars; we train our minds inward upon themselves, and discover emotions, ethical desires, and moral impulses — love, justice, pity RATS, LICE AND HISTORY 35 — that have no obvious relation to mere animal existence. The more we discover, the greater is our hopelessness of knowing origins and purposes.
The more our ingenuity reveals the orderliness of the nature about us and within us, the greater grows our awe and wonder at the majestic harmony which we can perceive more clearly with each new achievement of art or of science, but which — in ulti- mate causes or in goal — eludes us. To feel this awe and to wish to fit into the harmony of natural things, with a vision of the whole, is apparently a definite phenomenon of human psychology; it is the force that has engendered religions, just as the instinct to understand the material environment has produced science, and the impulse to express assthetic reactions has produced art.
It is obvious that religion begins where philosophy takes off from the solid shore of the exact sciences into speculative waters, the shallows of which are metaphysics. It is not entirely sensible in modern times, however, to speak of conflicts between religion and science which, to truly civilized people, have not existed for a long time. When perturbed ministers, like the Reverend Dr. Fosdick, passionately deny such a conflict, they are pounding the table and asserting that the earth is round. They desire to preserve the beneficent social and moral influences of an organized church in a world not yet ready for a purely ethical code.
And when distinguished minds, like Millikan and others, take wing from the ultimate peaks of exact science into the stratosphere of an old-fashioned heaven, they illus- trate the biological truth that the mind of man possesses ethical desires which the most highly developed knowledge 36 RATS, LICE AND HISTORY of science cannot satisfy — obviously, never will satisfy. It is not entirely a matter of accident that astronomers, physicists, and mathematicians are more prone than the biologist to fall into the lap of Mother Church or at least into that of one of her barren metaphysical sisters.
The biologist, in his work, is always confronted with the mystery of life. He learns a reverence for it which, com- pounded of wonder and awe, keeps him modest and will- ing to admit without despair that here is something quite amazing, worthy of continuous study, but, for the time being, beyond his capacities to comprehend. The sagacious physicists to whom I have alluded scamper back to God.
But they think they have reached a new understanding and have discovered a new and modern Jehovah, when as a matter of fact all they have done is perhaps to take away his beard and express his thunder in ergs. This, however, is too much to hope for in our present overpopulated world, for as fast as ministers like Dr. Fosdick throw overboard their ballast of mysticism in order to cross the shoals into a quiet harbour of reason, Millikan and other physicist-metaphysicians fish it out again to steady them in making the high seas of specula- tion.
Complete compre- hension could add very little. Bergson suggests that on another planet life might have been evolved by systems entirely different from our own. The element characteristic of substances that supply energy might have been other than carbon, and the ele- ment characteristic of living matter might have been other than nitrogen, leading to living bodies radically different from our own in chemistry, anatomy, and physiology. This may perhaps be true; but to believe it would require as- sumptions to which earthly observations give no clue.
In that transition between the dead organic combination and the similar one that is alive lies the great, incomprehensible mystery. What came before we can reasonably trace; what came after is at least open to inquiry in the records of existing living forms. In that leap from the dead to the living lies the mysterious break of continuity which defies our understanding.
Between the chemically definable protein molecule and the living bacterial cell there is a gap of understanding far greater than that between the first living cell and man. It is not easy to define life. An enzyme that could ex- pend energy and build up new energy for that which it expends, in automatically regulated cycles, would be alive — though soluble and not organized in cellular form.
There are invisible agents, parasitic upon plants and animals, which we know only by their activities. The ultra- microscopic virus agents, the mosaic disease which infects tobacco and potato plants, those which cause foot-and- mouth disease, rabies, yellow fever, infantile paralysis, smallpox, and many other destructive maladies, thrive in the living cells of higher beings and reproduce themselves in infinite generations, remaining true to type in habits of specific parasitism.
It is probable that some of the largest ones have been seen as just visible dots under the highest magnifications j but many of them have never been seen. It is assumed that they are living things, cellularly or- ganized, but we are not sure of thisj and the thought is at least reasonable that some of them are transitional things between true enzymes and formed cell-individuals. The evolutional transition from the dead organic com- plex to the cell may well have been a gradual one of infinitely small steps which may yet be uncovered. Modern observations of the bacteriophage phenomenon have at least given us the material for hopeful inquiry.
Did life originate spontaneously by such progressively complex associations of matter through enzymes — un- formed, regulated intermediaries, capable of building up and expending energy? Or did it come to our earth from elsewhere, — cosmically, — in which case it would have had to possess the capacity of resisting, without destruc- tion, exposure to temperatures ranging from absolute zero to incandescence.
We cannot deny these possibilities, but we have no clue to either. We are beginning to know that all the processes which take place in living beings are governed — though with more complexity — by the same physicochemical laws which govern the reactions in dead chemical systems. Yet this purely mechanistic understanding is insufficient for the final answer, and vitalism is reborn again and again to bridge the gap. The bacteria particularly nearest of recognizable cells to the stem of living things are still more important than we.
Omnipresent in infinite varieties, they perform fermen- tations and putrefactions by which they release the car- bon and nitrogen held in the dead bodies of plants and animals which would — without bacteria and yeasts — remain locked up forever in useless combinations, removed forever as further sources of energy and synthesis. Inces- santly busy in swamp and field, these minute benefactors release the frozen elements and return them to the com- mon stock, so that they may pass through other cycles as parts of other living bodies.
Some of them correct the excessive enthusiasms of their too thorough brethren, which break down nitrogenous substances to free nitrogen. In the soil and in the root tubercles of clover, peas, and other legumes, bacteria are busy fixing nitrogen into com- plexes ready for revitalization. Without the bacteria to maintain the continuities of the cycles of carbon and ni- trogen between plants and animals, all life would even- tually cease, plants would have no nitrates and no carbon dioxide with which to grow, cows would have no clover to eat, men would have no beef and vegetables.
Without them, the physical world would become a storehouse of well-preserved dead specimens of its past flora and fauna — as useless for the nourishment of the bodies of pos- terity as ugly and stupid thinking, petrified in books, is useless for the nourishment of its spirit. It was, in part, this same faith in pure observation which delayed for so many centuries a sensible approach to the problem of the origin of life. These things could be observed and, therefore, were true. Even the successful production of the homunculus 6. In spite of the immense literature of error which we shall presently consider, the ancient mediaeval specula- tors were less dangerous to understanding than are their modern representatives.
It is interesting to speculate what the Greeks might have achieved in another three or four hundred years of development if the empire building of the Romans, and the evolution of a Christian Europe out of barbarism, had not interrupted them. The one thing the Greeks lacked for the rapid acquisition of the necessary fundamen- tals of chemistry and physics was an experimental method- ology.
And this, it would seem, must have inevitably developed out of their geometry — as, indeed, it had already begun to do with Archimedes and a few others. It was the influence of mathematical thought which, in later centuries, gave rise to the method of the experimen- tal isolation of individual phenomena or their fractions. The Greeks were certainly closer to this in b. The world being as large as it is, it is probably neces- sary every now and then to mark time culturally for a thousand years or so.
And this is what seems to have happened in the single cycle of which we have histori- cal knowledge. As a matter of fact, while European civilization, from on, went far beyond the Greeks in scientific discov- ery, it is debatable whether in spiritual and moral devel- opment we have yet attained the standards of the Platonic philosophy, which was free from any scaflFoIdings of doctrine or supernatural buttresses. Just how badly the cultural spirit of the world has been dam- aged by the late war, it is too early to say.
Our forefathers based their opinions on the testimony of their five senses.
In the wake of Pasteur, Darwin, Emil Fischer, Willard Gibbs, and countless others, we are differentiating the problem. One of the great beauties of the scientific occupation is the pride of being a private in the great army of differentiators — the generals of which are never dead to their followers. Every objective gained, every trench dug, every citadel conquered, is a permanent advance in organizing the new territory for the coming of the next integrator.
Some day he may arrive and make a dead complex live. He may be the son of an English lord, of a Czechoslovakian peas- ant, of a Russian Jew, of a French barber, or — most unlikely — of an American broker. Thus is science the great democratic adventure. But when he comes, he will be hailed as King. The great mystery of life will be revealed as a physico- chemical process. But we know already that it is — though we have not succeeded in imitating it. And when we do, we shall be — philosophically — just about where we are now.
Its quest is a sort of forlorn hope of human endeavour, Indulged in by the intelligent impractical of every age. But it is a strange fact that the impractical among man- kind are remembered. Because of that quality which more than any other lends dignity to life: the in- stinct for happiness in understanding, — whether it be by intellectual or emotional perception, — which is the most incomprehensible of the attributes of mankind, and which neither the brutalities of individual nor the bru- RATS, LICE AND HISTORY 45 talities of national competition have ever succeeded in annihilating.
Among the impractical quests of man, none has been more alluring than that concerning the origin of life. Out of the mud of the Nile, by the heat of the sun, were engendered frogs, toads, snakes, and mice — for could one not see them oozing out of it in the warm months? The sacred, coprophagous scarabaeus was mysteriously fashioned out of balls of dung, and bees sprang from the putrefying cadavers of cattle.
He was followed in the same thoughts by Anaximander and Xenophanes. Rain water was added by Anaxagoras, which carried down fertile seeds from the infinite spaces. There seems to have been a general agreement on mud. But, in addition, new ones were being constantly added from the synthesis of sun-warmed organic matter. Parmenides, Empedocles, and Diogenes of Apollonia favoured mud and moist earth as the sources whence life sprang. Democritus, Epicurus, and their recorder, Lucretius, started something new. Everything on earth has life. The earth is the mother who, in her youth, gave birth to all living things — performing miracles of fecundity which gave origin to plants and animals and even to man.
But as she grew old much of her power was lost, and only trivial things like insects, reptiles, and other inferior be- ings were begotten from decaying organic matter, with the help of warm rain and sunlight. Archelaus believed that the putrefying spinal cords of animals and man were transformed into snakes. Diodorus, about 30 b.
Vergil seems to have believed the old story about the origin of bees from the dead bodies of steers. With the influence of Christianity, there was of course a considerable change in some of the views. All through the Middle Ages, the same type of rea- soning persisted. There was a little less naivete in some of the theories, but many others were more fantastic than anything antiquity was able to produce. The great physi- cian Avicenna believed that intestinal parasites were all produced from putrefying materials and moisture, and he completely accepted the origin of animals from properly combined elements.
Lippmann credits him with the state- ment that, as the result of a thunderclap, an incomplete calf dropped to earth from the sky. The pious William of Auvergne, Bishop of Paris, was quite willing to believe that worms and frogs were produced in this way, but questioned the matter in connection with horses.
A remarkable tale that kept cropping up again and again until relatively modern times was the belief in the origin of wild ducks and geese from barnacles. These birds came and disappeared and were never seen to breed, so that their origin became the subject of much speculation. One of the stories traced to Saxo Grammaticus was to the effect that the little geese came out of shells which grew on trees in the Orkney Islands.
The tale persisted until the latter part of the sixteenth century, when a Dutch sailor penetrated to the Arctic Ocean, where he observed and reported the nesting and breeding of the birds. Similar to this tale of the barnacle geese is the story of de Mandeville, who, in his Travels, speaks of a tree which bore huge, melon-formed fruit of which he him- self had eaten, and in which, when it was opened, he discovered a lamb.
The descriptions of travellers who began to pene- trate, in the late Middle Ages and early modem times, into all corners of the earth are responsible for innumerable stories of the same kind. The story of the vegetable lamb was not completely exploded until Linne, in the eight- eenth century, examined specimens of the various plants that were supposed to blossom as lambs.
The ideas of Paracelsus were, in regard to the origin of life, not materially different from those of his contem- poraries. However, the of Hippocrates was as- sociated with the Christian belief in the soul in explaining the manner in which God infused life into some of his creatures. Bacon was a firm believer in spontaneous generation, and Harvey, in , must be regarded as the first who clearly opposed the older views with his famous Ornma ex Ovo.
Kepler, wise as he was, believed that plants could grow out of the earth without ancestors, and fish could be produced by spontaneous generation in salt water, just as comets could arise in the skies. The honours are with Redi, though the conclusions are the same.
Rats, Lice and History / Edition 1
Leibnitz, in , expresses the conviction that spon- taneous generation is impossible, and that neither plants nor animals could have originated from a chaos of putre- faction. Leibnitz was frankly agnostic in other expressions on this problem, Descartes, who was familiar with the work of Leeuwen- hoek and of all other important naturalists of his time, gave little thought to the origin of living things, but speculatively hit the nail on the head by taking for granted that there may be a world of minute living things from which life of other kinds can develop by a sort of evolu- tion.
Between the end of the eighteenth century and the be- ginning of the nineteenth, an accumulation of accurate observations began to limit the field of speculation, and, indeed, in surveying the history of the thoughts of men upon this problem, it is quite apparent that here — as in all sciences — there has been an inverse ratio between speculation, on the one hand, and the accumulation of observations on the other. Lippmann men- tions the amusing fact that one of the important observa- tions on this subject was made in by a chef in a Paris kitchen, Appert by name, who preserved foodstuffs by heating them and putting them into hermetically sealed pots — an observation which was in line with a similar one made by Scheele on the preservation of vinegar by boiling and sealing in vessels.
There were throwbacks, like Needham, but the modern era had begun and the ex- perimental method was soon to take charge of the de- velopment of biological thought. Modern biology was born when scholars began to concentrate their complete attention upon the study of the manner in which life existed, and limited speculation entirely to the construc- tion of trellises along which new experimentation might grow. The final demonstration, by Pasteur, that alleged observations of spontaneous generation were attributable to experimental error marked the ending of biological mediaevalism.
Thus, biology began as it will end — as applied chemistry and physics. It will be of profit,' in maintaining this thesis, to set forth, in the bare bone, the structure of biology as it has come down to our time. The reader of imagination will remember with sympathetic admiration the unnamed mul- titude of patient toilers, the unknown soldiers of the great struggle toward the truth, who helped to forge the tools for the hands of genius. Everyone who thinks about these matters can construct a table of significant achievements for himself, and no two will be alike.
But since this book is written more for our own amusement than for anyone who may possibly buy it, we set down in chronological order those conquests of understanding which seem to us to have most directly contributed to the modern views of the mechanism of living things. We give them without explanations, since those to whom such matters are unfamiliar may look them up in any up-to-date history of science. Lavoisier demonstrates the indestructibility of matter. Quantitative chemistry begins; respiration is re- cognized as akin to combustion.
KirchhofF finds that starch can be converted into glucose by the action of dilute sulphuric acid, which itself remains unchanged. Cuvier lays the foundation of palaeontology. Synthesis of an organic compound urea by Wohler. Discovery of the mammalian ovum by von Baer. The birth of modern embryology and the first great for- ward step in this direction since Harvey. Schleiden demonstrates the cell struc- ture of plants, and Schwann the cell structure of animals.
Cagniard de la Tour proves that fermentation is dependent on yeast cells. Von Mohl describes protoplasm. Die T hierchemie, and so forth, on the application of chemical methods to animal tissues j also containing the important conception of animal heat as combustion.
The beginning of the application of biochemical and physiological methods to the living animal. Darwin and Wallace advance the ideas of or- ganic evolution, bringing in their train the energetic de- velopment of comparative anatomy, embryology, and ra- tional systematology. Final refutation of the experiments on sponta- neous generation by Pasteur.
The birth of colloidal chemistry by the studies of Graham. Pasteur defines the dependence of fermentation and putrefaction upon living organisms. It was the foundation of the science of ge- netics. Discovery of osmosis by Pfeffer. Development of modern bacteriology and immunology, with the growth of technique for the study of life in its simplest available form. Rubner applies quantitative methods to the study of the heat value of food materials. Beginning of the syntheses of organic matter by Emil Fischer — glucose, fructose, and finally polypeptide, which is one of the higher cleavage products of protein.
With the era of Fischer begins the true structural knowl- edge of the proteins. Elucidation of the carbon-nitrogen cycle by Hell- riegel and Wilfarth. First discovery of an ultra- virus mosaic disease of plants , by Beijerinck. First discovery of ultra-virus causing disease in animals foot and mouth disease , by Loffler and Frosch. Beginning of knowledge of the effect of radiant energy X-ray, ultra-violet on life processes.
Discovery of hormones or physiological messen- gers; internal secretions defined by Bayliss and Starling. Those responsible: Sorensen, Loeb, Henderson, Clark, and many others. Vitamins discovered by Hopkins and Funk. Whether these substances are alive or dead is at present almost an academic question. Based on experiments of Steenboek and of Hess. The crystallization of enzymes, the credit for which goes to Northrop. All this may seem remote from the story of typhus fever; but only to those who are impatient for the sen- sational events in a turbulent narrative.
Rats, Lice and History : Hans Zinsser :
Without the de- velopments here recorded, we should now know little about the true nature of the subject of our biography. CHAPTER IV On 'parasitism in general, and on the necessity of consider- ing the changing nature of infectious diseases in the his- torical study of epidemics; with a brief consideration of syphilis as an illustration of this contention. T hese matters have direct bearing on our biography, since we must pro- ceed as though we were writing of a man for readers ignorant of the race of men I Nothing in the world of living things is permanently fixed.
Evolution is continuous, though its progress is so slow that the changes it produces can be perceived only in the determinable relationship of existing forms, and in their palaeontological and embryological histories. Though the processes which determine evolutionary change do not appear as simple to-day as they seemed when the Origin of Species was published, it would occur to no biologist to assume that any living form is perma- nently stabilized.
On purely biological grounds, there- fore, it is entirely logical to suppose that infectious dis- eases are constantly changing, new ones are in the process of developing, and old ones being modified or disap- pearing. Parasitism originated in dim primordial antiquity as a consequence of habitual contacts between different living things.
Para- sitism, in its origin, means a breaking down of that opposition which, normally, every living cell complex offers to invasion by another living entity. They develop and remain free from invasion in a pond which is swarming with bacteria and Protozoa. A frost kills them overnight, and within a few hours their substances have become culture media for innumer- able micro-organisms.
And once begun, the further evolution of parasitism can proceed in an almost unlimited variety of directions. Parasitism represents that phase of evolutionary change which lends itself most easily to analysis. There are few parasites which cannot be traced with considerable clear- ness to some free-living ancestral stock, either still existent or available in fossil form.
From this point of view, the study of parasitic adaptation is one of the most important buttresses of evolutionary theory. Each instance represents a miniature system in which the host is the world by which the parasite is moulded. It would be surprising, therefore, if new forms of para- sitism — that is, infection — did not constantly arise, and if, among existing forms, modifications in the mutual adjustment of parasites and hosts had not taken place within the centuries of which we have record.
But it is relatively easy to induce fatal infection with an organism of ordinarily low parasitic powers by reducing the resistance of an individual host. This has been repeatedly done since the time of Pasteur. Such changes in both directions occur in the bodies of infected animals, can be produced at will in test-tube experiments, and can be correlated with morphological and chemical changes in the bacteria themselves. The subject is one of the most important fields of contemporary investigation, and the results achieved have profoundly modified conceptions of infection.
To pursue it further would obviously lead us into technical discussions, more suitable for a text- book of bacteriology. The matter is mentioned in the pres- ent connection merely to support our contention that the historical study of infectious disease must, hereafter, take into account the fact that parasitic adaptations are not static, and that extraordinarily slight changes in mutual adjustment between parasite and host may profoundly alter clinical and epidemiological manifestations.
There is a wide range of delicate gradations between saprophytism and parasitism, and the biological and chem- ical properties along which adaptation changes progress are — to some degree — dependent upon whether an organism that causes disease in man and animals has re- tained the capacities for life in nature, whether it passes through intermediate hosts, or whether it is so closely adapted to an individual host that it cannot exist apart from him, and perishes when the host dies, unless trans- mitted to another.
In such cases, there is an un- interrupted transmission from host to host, the parasite is never subjected to environments other than those to which it is most perfectly adapted, and, in consequence, evolution may progress in a single direction — toward a more perfect mutual tolerance between invader and invaded. This condition exists, for example, in certain trypanosome infections of rats, in the spirochastosls and sarcosporidial infections of mice, and in a large variety of other conditions of animals and plants. In these, the in- fected animal shows practically no signs of discomfort or pathological change in reaction to the parasite.
The principles have been thoroughly discussed by Theobald Smith. In animal populations, the first impact of a new virus is upon individuals of all ages. The survival of some of them is a matter of chance, depending on genetic differences or the accidental overlapping of immunity derived from other — possibly related — diseases. The extinction of many species of animals in past ages is best explained by freshly introduced parasites. In man, a condition which illustrates these principles is syphilis.
There is little doubt that when syphilis first appeared in epidemic form, at the beginning of the six- teenth century, it was a far more virulent, acute, and fatal condition than it is now. Uninterrupted transmis- sion from one human being to another, without intervals of extraneous existence in the course of almost five hun- dred years, has led to gradual mutual tolerance, one of the consequences of which has been an increasing mild- ness of the disease. If mankind could be kept as thor- oughly syphilized in the future as it has been in the past, another thousand years might produce a condition not unlike the present spirochsetosis of mice, in which a peri- toneal puncture of almost any bon vivant would reveal the presence of a treponema pallidum infection of which the host is all but unconscious.
Arsphenamin has probably ruined this prospect. We omit reference to specific instances of this among our contemporaries only to avoid, for our publishera, the vulgar embarrassment of libel suits. Modern treat- ment, and the agilities of expert testimony, render legal proof of such contentions hopelessly difficult. Typhoid and dysentery bacilli, cholera spirilla, the streptococci and staphylococci which cause surgical infections, and many other micro-organisms can survive for longer or shorter periods separated from the hostj and the circum- stances under which this is possible, the length of time of survival, and the alterations which take place in them during such periods, are all of them of the greatest im- portance to the student of epidemics.
Yet even in such in- fections by half-parasites — if the infection is widely disseminated — the factors discussed above become active, and successive generations tend to develop increased resistance. For human infections, many examples of this could be cited — one of the most illustrative that of tu- berculosis, in which the high susceptibility of aboriginal peoples as compared with resistance of the thoroughly tuberculized populations of European origin is a well- known fact.
Here, as in bacterial disease, there is a lively interchange of parasites between man and the animal world.
Indeed, since we can neither see these infectious agents nor cultivate them, except in the pres- ence of living tissues, the only opportunity we have of subjecting any of them to systematic study is by finding some animal in which disease can be produced. As a con- sequence of such study, it has appeared that these agents, even more than bacteria, are of an extraordinary biological plasticity, and can often be modified by simple labora- tory manipulation. The transformation of smallpox virus into vaccinia by passage through cattle is far more pro- found a change than the alteration which differentiates the plague of Athens from smallpox as we know it to- day.
The mere passage of the virus through another species has — in this case — so altered it that it w'ill no longer cause more than a negligible local reaction in man; but, nevertheless, it retains the fundamental bio- logical properties by which it immunizes him. In the same way, the passage of rabies virus through rabbits rapidly increases its virulence for these animals, slightly diminishing it at the same time for monkeys and man.
Yellow-fever virus, injected into the brains of mice, ceases to produce typical yellow fever, but causes a form of encephalitis which, thereafter, can be carried in series from mouse to mouse. Carried back to monkeys, even though passed through mosquitoes, it retains its affinity for the nervous system. While this process is probably continuing, it is too gradual and slow to be traceable from an established disease to its ultimate origin. There remain two chief sources of new diseases within historic periods: namely, the modifications of para- sitisms already existing in man by gradual adaptative changes in their mutual relations; and the invasion of man by parasites, well established within the animal king- dom, by new contacts with types of animals and insects to which mankind was not previously exposed.
The Australian X disease — a po- liomyelitis-like condition — was probably contracted by man from sheep, and tularaemia — a disease not recog- nized before , and at present spreading through the United States — is acquired from a number of animal sources. This is a large field, which we have no intention of discussing except in so far as it concerns the subject of our biography — typhus fever. Entirely apart from the medical and sani- tary aspects of the typhus-fever problem, the circum- stances of its transmission are of extraordinary biological interest, because they give us — more than any other disease cycle — the opportunity of studying the evolu- tion of a parasitism which has taken different channels in various parts of the world, adapting itself to the diver- gent circumstances of local insect and rodent distribu- tion.
Typhus fever is one of the Rickettsia diseases which form a closely related group. The minute, bacillus-like organisms which cause these conditions Rickettsiae — named after Ricketts, an American who died while in- vestigating typhus in Mexico are closely related to a number of similar and harmless micro-organisms which are habitually found in the bodies of many insects.
It is, for this reason, not unlikely that the original parasitism of these organisms was acquired by insects, and from them was passed on to some of the lower animals rodents and so to man. These conditions are discussed at some length in a later chapter. The more thor- ough the saturation, the more apparent the results. The simplest demonstration of such changes is the rapidity of spread and the virulence of a disease when it is first introduced into the reservoir of an aboriginal — that is, entirely susceptible — population.
When measles first came to the Fiji Islands in , as a result of the visit of the King of the Fijis and his son to Sydney in New South Wales, it caused the death of 40, people in a popula- tion of about , Another example is the terrific violence of smallpox when first introduced among the Mexican Indians by a Negro from the ship of Narvaez. The virulence of tuberculosis for Negroes, Eskimos, and American Indians living in contact with whites is another case in point. Any number of illustrations of this kind might be cited.
But even among crowded, thoroughly in- fected populations, diseases have changed within relatively short periods. Scarlet fever has become definitely milder throughout Western Europe, England, and America since about The same is true of measles and diphtheria, as regards both incidence and mortality. The change began well before modern preventive methods had exerted any noticeable influence. Perhaps it is not an accident, however, that, in the case of diphtheria, — in the control of which modern bacteriological methods have been most effective since the late nineties, thus creating interference with normal evolution, — we are just beginning to observe the return of excessively toxic and deadly cases, reported in increasing numbers from Central Europe.
Before the last decade of the fifteenth century, there are few reliable records of syphilis in Europe. The subject has been greatly disputed, and many passages — especially in ancient Hindu manuscripts — have been interpreted as signifying that venereal sores similar to those characteristic of syphilis were known in the ancient world. Medical historians have cited many observations which they regarded as indicating the ancient existence of syph- ilis; but most of these, on close scrutiny, turn out to be unconvincing. Careful transla- tion of these sonnets, with particular scrutiny of the ex- pressions in them which are diagnostically significant, leads to the conclusion that they are merely very nasty poems, with no precise reference to the disease.
It is not, of course, possible to exclude with certainty the ancient existence of a form of syphilis milder than that which swept over Europe in the early sixteenth cen- tury, and Haeser — who does not subscribe to the opin- ion of the American origin — believes that syphilis may have been prevalent to a limited degree and in a less virulent form since ancient times. There are few descriptions, however, in which it is possible to trace the relationship of a venereal infection to secondary and tertiary consequences in other parts of the body.
This Haeser is inclined to believe is due to the unwillingness of doctors and patients to attribute venereal origin to conditions occurring several weeks after infection and, similarly, he believes that the later and usually mild manifestations may have been overlooked, or described in unrecognizable form.
There are a few accounts cited by him which lend weight to his views. The American origin of syphilis forms the basis of a theory that has become widely prevalent, and although it cannot be proved beyond question that America was the source from which the disease reached Europe, it is more than likely that it existed in the Western Hemisphere and that early explorers may have been infected by inter- course with coastal Indians.
In this connection, much has been made of lesions on bones found in the graves of the mound builders of Ohio and other regions — notably. Pro- fessor Herbert U. Williams, who has recently sifted the evidence, with attention both to the antiquity of examined bones and to the trustworthiness of pathological examina- tions, believes that there is unmistakable evidence of syphilis in many of these lesions. In the Life of Christopher ColumhuSy by his son, Ferdinand, there are included passages from the writings of a hermit of the order of Saint Jerome, — Pane, by name, — written at the time of the second voy- age of Columbus.
From the manuscript of the last named writer, Williams quotes a paragraph not represented in the printed editions, — left out for unknown reasons, — which is of exceptional importance. And as it is a secret disease never seen. The the- ory of American origin, however well-founded in other respects, meets with an almost unanswerable objection in the shortness of the period which elapsed between the return of Columbus and the syphilis epidemic which broke out in Naples in Moreover, Julien, a French naval surgeon, has recorded that syphilis was more common among the coastal tribes who were in contact with Euro- peans than among the Indians of the interior, even in the early days of exploration of the Western Hemisphere.
It is not at all unlikely that a mild form of syphilis oc- curred all over the world, including China according to Dudgeon and Japan according to Scheube , long before the fifteenth century. This is the view favoured by Haeser, Hirsch, and other learned scholars. While, thus, there remain legitimate differences of opinion concerning the problem of origin, there is no doubt whatever that syphilis flared up in a sudden, intense, and widespread manner shortly after the time when Charles VIII of France led his army through the South of Italy against Naples.
The city was taken by the French in February , and the disease promptly appeared among the troops and the burghers. As the army dis- persed, deserters, camp followers, and demobilized sol- diers spread the infection far and wide, and, because of the malignancy and disgusting character of the malady, it was the custom of the day to blame it upon the enemy. Some- thing must have happened at that time, apart from war and promiscuity, — both of which had been present to an equal degree many times before, — which converted a relatively benign infection into a highly virulent one.
The history of the subsequent fifty years strikingly illus- trates the rapidity with which adaptive changes may take place. It is probable that in all parasitisms these alterations of mutual adjustment begin with considerable velocity, the curve flattening out progressively with the increasing number of passages of the parasite through the same species of host.
According to Scharfenberg, it was a feverless disease characterized by pustular and ve- sicular eruptions with extensive ulceration. Though the first ulcerations usually appeared on the genitals, this was not always the case. Primary contact infections oc- curred on many other parts of the skin, and the disease was often transferred from mothers to children in ordinary association.
Van Helmont, Ozanam tells us, believed that it was started by the intercourse of a man with a mare that had glanders. Linder thought that it started by a similar relationship with a monkey, and Manard thought it came from marriage with a leper. Crusts formed, and the sick presented so dreadful an appearance that their companions abandoned them and even the lepers avoided them. Extensive losses of tissue in the nose, throat, and mouth followed the skin mani- festations, and in the train of these came painful swellings of the bones, often involving the skull.
The disease it- self, or secondary infection, caused many deaths. In sur- vivors, emaciation and exhaustion lasted for many years. Within a little more than fifty years, the disease had already changed. The poem was finished in its earlier form in , and presented to the Sainte-Beuve of his time, Bcmbo. Within the next five years it was rewritten and enlarged, and a third book was added, which deals chiefly with the treatment of syphilis with guaiac. However, in both the earlier and the later versions, Fracastorius indicates in an allegorical manner that mercury is the best remedy.
I mean that, within the last twenty years or so, fewer pustules began to appear, but more gummata; whereas the con- trary had been the case in the earlier years. Moreover, in the course of time, within about six years of the present genera- tion, another great change has taken place. I mean that pustules are now observed in few cases, and hardly any pains — or much less severe — but many gummata. CHAPTER V Being a continuation of Chapter IV, but dealing more particularly with so-called new diseases and with some that have disappeared I It is obvious that when one searches the ancient and mediaeval literature for the existence of maladies in which differential diagnosis is difficult even to-day, one is likely to make many mistakes.
Accurate descriptions are rare and, even when details of symptoms and courses are as accurate as those to be found in Hippocrates, there is a total lack of the laboratory evidence which is often in- dispensable for certainty. The problem is particularly confusing in connection with epidemic infections of the nervous system, many of which are generally regarded as new diseases at the present time.