GERM THEORY OF DISEASE. 



443 



few hoars, but that the blood appeared to bo 

 free from bacterial life on microscopic exami- 

 nation, and was incapable of producing symp- 

 toms of disease in other animals inoculated 

 witli it. Tlie bacteria introduced were found 

 Htill confined in the subcutaneous cellular tissue 

 of the dead subjects. He further found that a 

 certain amount of the fluid required to bo in- 

 j.-cted before the disease was produced. Ho 

 tlu re-fore concluded that these symptoms were 

 not due at all to living germs, but to a soluble 

 poison septin or sepsin contained along with 

 the bacteria in the putrid fluid. Another dis- 

 ease, however, was produced in about one third 

 of the cases, no matter how small the quantity 

 of the injected fluid. This disease ran through 

 a certain order of characteristic symptoms, 

 and was followed after a definite period by 

 death. Taking the blood of one animal to 

 infect another, he produced this form of trau- 

 matic septicaemia in seventeen successive sub- 

 jects. He found that only house-mice were 

 susceptible of the contagion, while on rabbits, 

 and even on field-mice, the infected blood would 

 have no effect. In the blood of the infected 

 animals he detected swarms of bacteria of a 

 definite form and size, bacillus-like in structure, 

 which were evidently the contagion of this pe- 

 culiar disease. 



No other bacteria injected with these bacilli 

 were able to live and multiply in the living 

 tissue ; but occasionally a form of micrococcus 

 was observed which multiplied with great ra- 

 pidity, forming chains in the subcutaneous tis- 

 sue, while the bacillus lived and spread in 

 the blood. This micrococcus when injected 

 into the ear of the mouse produced a dis- 

 tinct disease necrosis of the tissues of that 

 organ. It found here so congenial a medium 

 to propagate in, that it spread through and 

 through the tissues until they were completely 

 destroyed. This disease could never be pro- 

 duced in the house-mouse unless its blood was 

 simultaneously infected with the septicaemia 

 bacillus ; but the field-mouse, which is not lia- 

 ble to septicaemia at all, could be infected from 

 the house-mouse with the micrococcus, and 

 the house-mouse when inoculated from an in- 

 fected field-mouse then harbored the parasite, 

 which spread in its chain-like forms with the 

 same rapidity and produced the same symp- 

 toms of progressive necrosis as in the field- 

 mouse, or in the house-mouse accompanied by 

 septicaemia. 



Injection of putrid blood into rabbits pro- 

 duced an entirely different effect. Abscesses 

 were formed in the subcutaneous tissue, which 

 increased gradually in size, causing death in a 

 few days. These abscesses were found on ex- 

 amination to be surrounded by a thin layer of 

 micrococci in the zooglaa state. The cheesy, 

 granular contents of the abscesses were prob- 

 ably derived from the zoogloea and the dead 

 tissues invested by them. A little of the mat- 

 ter of the abscess diffused in water invariably 

 produced the disease in healthy subjects ; but 



the injection of the blood of the disensed rab- 

 bits produced no effect. The artificial produc- 

 tion of pyaemia in rabbits revealed the pres- 

 ence of micrococci, but they were neither in 

 chains nor in zooglcaa films, and differed in 

 size from those attending the other diseases. 

 They occurred either singly or in pairs in thu 

 blood-vessels, surrounding the corpuscles, and 

 formed accumulations which sometimes caused 

 a stoppage in the vessels. By the injection of 

 putrescent infusions both septicaemia and ery- 

 sipelas were produced in rabbits. Septicaemia 

 was accompanied by a distinct form of micro- 

 coccus, and could be transmitted from one 

 animal to another. Erysipelas showed the 

 presence of small bacilli, but could not be 

 transmitted. 



Pasteur believes that he has discovered in 

 recent researches the microscopical organisms 

 which produce puerperal fever and malignant 

 pustule. The parasite which causes puerperal 

 fever he describes as an entozoOn containing 

 two, four, or six cells united together. The 

 cells have an average diameter each of two 

 thousandths of a millimetre. His researches 

 into the cause of malignant pustule have con- 

 vinced Pasteur that this disease is engendered 

 by the bacterium which Davaine discovered in 

 1860. The method of investigation was by 

 obtaining the organisms to be observed by cul- 

 tivation. This method, which he first em- 

 ployed in 1857, is the only means of obtaining 

 specimens in a state of purity. He took a 

 minute drop 6f blood from a case of malig- 

 nant pustule, and sowed it in a liquid propi- 

 tious for the development of the organisms 

 the froth of beer-yeast. By repeatedly in- 

 fecting fresh yeast-frotli with a drop of that 

 which he had before infected, he could keep 

 on hand for years a constant supply of the or- 

 ganisms. By introducing this liquid into the 

 blood of guinea-pigs, sheep, and certain other 

 animals, malignant pustules were reproduced 

 in them. If he filtered the liquid through a 

 plaster filter, the germs remained on the filter- 

 ing substance, with which the disease could be 

 inoculated, but not with the filtered fluid. 

 The poultry cholera can be cultivated and 

 fowls infected in the same manner. Puerpe- 

 ral septicaemia could probably also U> j>ivserved 

 by culture and inoculated from the medium of 

 cultivation. Thus the evidence in favor of the 

 germ theory is rapidly accumulating. 



The facts that the above diseases can be 

 communicated from one animal to another by 

 the injection of infinitesimal quantities of the 

 diseased blood or tissue, that each disease has 

 its own characteristic form of bacterium, and 

 that they multiply at a sufficient rate to ac- 

 count for the symptoms, seem to prove the 

 parasitic origin of these diseases. There is 

 conflicting evidence which leaves the question 

 of a living contaginm still in doubt, even in 

 regard to some of the diseases in which the* 

 presence of a characteristic microphyte lias 

 been established. Pan urn, Richardson, and 



