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isms in nature, but he observed that we drink bacteria in water, which, although small, cannot penetrate into the blood.
Van Leeuwenhoeck's successors described and classified these "infusion animals” and his discovery was quickly made known and used as the explanation for many diseases.
From the earliest investigations into the life-history and properties of bacteria these micro-organisms have been thought to play an important part in the causation of infectious diseases. The doctrine of contagium animatum was based upon the discoveries of Kircher and Van Leeuwenhoeck, and the “animalculæ" then observed in organic materials were believed to be the cause of the great epidemics of the day, such as the plague. Shortly after these first investigations, Lange and Hauptman advanced the opinion that puerperal fever, measles, smallpox, typhus, pleurisy, epilepsy, gout and many other diseases were due to animal contagion, and Nicholas Audry and Linné thought that smallpox and venereal disease were caused by these organisms, and that Audry cured himself of the latter disease by killing the worms with mercury.
In 1718 Lancise assumed the same cause for malaria. In fact, · so widespread became the belief in a causal relation of these minute organisms to disease that it soon amounted to a veritable craze, and all forms and kinds of diseases were said to be produced in this way, upon no other foundation than that these organisms had been found in the mouth and intestinal contents of men and animals, and in water.
Nearly a century elapsed before the subject was again considered and before any attempt was made to define the character of these minute organisms and to classify them. The first to make such an effort was Otto Friedrich Müller, of Copenhagen, who applied many of the names we still use, and he established, as well, genera which are still recognized. He called these microscopic organisms Infusoria instead of vegetable forms, and thus made the mistake which aroused considerable debate and misunderstanding, since the infusoria are unicellular animal organisms.
During the eighteenth century the question of spontaneous generation of bacteria arose. The theory of the spontaneous generation of insects had been previously overthrown by Swammerdam (in 1669), and the whole subject was gone over again in relation to the more minute bodies—the bacteria. The conclusions of Needham, who experimented on the spontaneous generation of "infusion animals," met with general acceptance until Spallanzani (1769), the greatest experimenter of his age, overthrew his claim so completely that Appert (1809) was able to devise a successful method for the preservation of food materials on the basis of their work. This was the first practical result of the older bacteriology.
New opponents continued to arise until Franz Schulze (1836), Schwann (1837), Schröder and Von Dusch (1854-1861), Van der Brock (1857), and Pasteur (from 1857 onward), overthrew by. conclusive evidence every argument for spontaneous generation and demonstrated that all microbes arise by legitimate descent out of germs of the same kind. Harvey's law, Omne vivum ex 070, was therefore fully established. Perty was the first to show that the bacteria belong to the vegetable and not to the animal kingdom. The fundamental work of Ferdinand Cohn gave the idea a further blow.
The principal advance in the first half of the nineteenth century was the demonstration of the fact that the bacteria stood in a certain relation to the most highly organized beings, especially to man. Stimulated by the establishment of the fact that fermentation and putrefaction were due to the action of living organisms reproduced from similar pre-existing forms, the study of the causal relation of these micro-organisms to disease was taken up with renewed vigor. Reference has already been made to the cpinions and hypotheses of the earlier observers as to the microbic origin of infectious diseases. The first positive grounds, however, for this doctrine, founded upon actual experiment, were the investigations into the cause of certain diseases in insects and plants. Thus Bassi, in 1837, demonstrated that a fatal infectious 'malady of the silk-worm-muscardine—was due to a parasitic micro-organism. Pasteur later devoted several years' study to an exhaustive investigation into the same subject; and in like manner Tulasse, in 1864, and Kühne, in 1855, showed that certain specific affections in grains and vegetables, e. g. in the potato, were due to the invasion of parasites.
Very soon after this it was demonstrated that micro-organisms were the cause of certain infectious diseases in man and the higher animals.
Bacteriological research has always been of special interest to physicians. Many of the most distinguished physicians of the day, in the earlier history of the science, concerned themselves in
these investigations, and the progress made during the last ten to twenty years has been largely due to their work.
Discovery of Anthrax Bacillus.-Davaine, a famous French physician, has the honor of having first demonstrated the causal relation of a micro-organism to a specific infectious disease in man and animals. The anthrax bacillus was discovered in the blood of animals, dying from this disease, by Pollender, in 1849, and by Davaine in 1850; but it was not until 1863 that the last-named observer demonstrated by inoculation experiments that the bacillus was the cause of anthrax. These experiments were subsequently confirmed by Pasteur, Koch and others.
Koch advanced this line of work in a remarkable degree by the methods he devised about 1880. One of the greatest services that he has rendered to bacteriology, is his invention of methods of pure culture on solid media by means of which such isolated colonies, originating from a single germ, can be cultivated at will and obtained free from any admixture with germs of any other kinds. The isolation of pure cultures of a large number of micro parasites was achieved and in many cases it was demonstrated by successful transfer to animals that the microbes had great significance in the origination of those diseases in which they were observed. In this series of investigations, Koch's discovery in 1882 of the germs of tuberculosis stands out conspicuously as especially epochal.
Prior to Koch’s discovery, many original investigators were busy in other directions. Obermeier, in 1873, discovered the spirochæte of relapsing fever. Von Recklinghausen, Waldeyer, Klebs and Weigert had already found bacteria in the tissues in various diseases when Koch in 1878 published his investigations upon wound infections. According to his conclusions, every special disease had corresponding to it a special disease germ just as there appeared to be a special germ for each fermentation. Pasteur's comprehensive work had built the foundation for the conception that each special fermentation and disease was causally dependent upon a special micro-organism. The brilliant results which Lord Lister obtained, in 1863-1870, in the antiseptic treatment of wounds, to prevent or inhibit the action of infective organisms, exerted a powerful influence on the doctrine of bacterial infections, causing it to be recognized far and wide and gradually lessening the number of its opponents.
Neisser, in 1879, discovered the “gonococcus” in gonorrhoeal discharges. In 1880, Eberth and Koch independently observed
the typhoid bacillus, but it was not until 1884 that Gaffky published his important researches, and proved the etiological relation of this bacillus to typhoid fever.
Sternberg and Pasteur independently observed (1880) a pathogenic micrococcus in saliva, which was subsequently proved by Fränkel and others (1885) to be the organism most commonly associated with acute croupous pneumonia and now recognized as the usual cause of that disease.
The year 1882, made memorable by Koch's discovery of the tubercle bacillus, will also be remembered as the year when Pasteur published his investigations upon “rouget” or hog erysipelas. In this year, also, his first communication upon rabies appeared. In 1882, also, Loeffler and Schütz discovered the bacillus of glanders.
In 1884, Koch discovered the cholera spirillum, and Loeffler the diphtheria bacillus, though it had been observed by Klebs the year before. The tetanus bacillus was also discovered in 1884 by Nicolaier, although it was not until 1889 that it was obtained in pure culture by Kitasato.
In 1892, Pfeiffer and Canon independently discovered a bacillus which is believed to be the specific cause of influenza.
These include some of the most important pathogenic bacteria, the discovery of which is of special interest to us, although under the subject of Etiology we shall refer more particularly to them as well as others.
Like all branches of theoretical and practical medicine, bacteriology owes much of its early advancement to the leaders of the Prussian Army Medical Department. The Prussian surgeon Struck, as head of the Imperial Board of Health in Berlin, took the initiative in creating the first standard working laboratory which served as a model for all subsequent institutions. Without this powerful aid Koch could not have developed his pioneer methods. Earlier pupils of the Army Medical School, like Helmholtz, Virchow, Reichert, Leyden, Fisher, and Nothnagle, had already achieved important professional positions; and upon the establishment of hygienic and bacteriological laboratories and the creation of professorships, German army physicians, and chiefly, indeed, those who were pupils of this institute, appeared as workers of the first rank. Among these we may name Behring, Buchner, Fischer, Gärtner, Gaffky, Loeffler, R. Pfeiffer, and Schrötter.
In order to appreciate the vast difference between the present existing methods of diagnosis and treatment and those which were in vogue prior to the discovery of the bacteriologists, let us go back to the early part of the century just passed.
In the Fourth Volume of the “Medical Repository” is printed a paper of special interest to us, entitled “The Improvements, Progress and State of Medicine in the Eighteenth Century.” This paper was read before the Medical Society of South Carolina on the first day of the nineteenth century. No doubt the writer made as much of his subject as possible, and the list of the discoveries and developments of the hundred years then just passed was as follows: Improvements in anatomy in the preparation of specimens; new operations in surgery; instruction of the deaf; experiments with poison on living animals; establishment of humane societies; cool regimen in fevers and smallpox; establishment of medical societies, hospitals and infirmaries; improvement and simplification of the materia medica; discoveries in chemistry; triumph of physic over smallpox by inoculation and over scurvy by vegetable diet and oxygen; and the abatement of plague and pestilential fevers. At that time these were considered wonderful advances, but appear to us, no doubt, as will a description of the advances made during the nineteenth century to an observer a hundred years hence.
Treatment of Disease in the Early Part of the Nineteenth Century. In the early part of the nineteenth century the recognized methods of treatment were blood-letting, blisters, cathartics, and emetics, without any reference to the diseased condition, and it was heresy to advocate any other methods. People who fell victims to disease died, often because of the heroic measures employed to counteract the maladies which afflicted them. Indeed, many physicians began to feel that more patients would recover if nature were left, unaided, to fight the disease. Few, however, had the temerity to voice these sentiments, and the few that did suffered ostracism because of their expressed views. In England Sir John Forbes incurred the displeasure and contempt of his fellow-practitioners by expressing his belief that no treatment at all was better than the treatment then in vogue. This was the condition of affairs in the early part of the nineteenth century, and it is little wonder that when Hahnemann began to teach his doctrines he soon found many followers.
Domination of Systems of Medicine. At the beginning of the nineteenth century, the so-called systems dominated the practice of medicine, for every prominent man considered it incumbent upon prominence in their profession to promulgate a complete