CHAPTER IV. 

 Bacteria as the Causes of Disease. 



Anthrax — PoUender — Davaine— Rayer — Laplat and Jaillard's Observations 

 controverted by Davaine — Pyaemia and Septicsemia — Salisbury on 

 Bacteria as the Cause of certain Fevers— Johanna LUders' and Hallier's 

 observations on Pleomorphism or PoI)nnorphism — Burden Sanderson, 

 Hoffman, and others, state that there is no Connection between Bacteria 

 and the Higher Fungi — Demonstration of Infective Element in Anthrax 

 Blood — Bacteria found in Organs in certain Diseases — Sarcina in 

 Stomach — Specific Organisms — Specific Activities. 



The bacterium which, in its relation to the cause of a specific 

 infective disease in man and the higher animals, has been 

 most thoroughly studied is the Bacillus anthracis, an organism 

 which, not only on account of its size but also because of its 

 powers of adapting itself to conditions both outside and 

 within the body, has been recognized comparatively easily, 

 and cultivated in artificial fluids and on other nutrient media 

 in which it grows luxuriantly, so that it has been possible to 

 study more or less carefully its morphological and physio- 

 logical characters. This bacillus was observed by Pollender 

 as early as 1849 in the blood from the enlarged and pulpy 

 spleens of cows that had succumbed to anthrax or splenic 

 fever. He recognized that the bacilli were not fragments of 

 broken-down vessels or coagulated fibrin, as had been sug- 

 gested, but that they were probably small vegetable organ- 

 isms similar to those described by Dujardin as "vibrio 

 bacillus," and he suggested that it was quite possible that 

 these organisms were in some way or other associated with 

 the appearance of anthrax disease. 



In the following year, and before Pollender's description 

 had been published (his full description was published in 

 1855), Davaine and Rayer described motionless thread-like 

 organisms and rods in the blood taken from animals affected 

 with splenic fever. These observations were confirmed by 

 other observers, but it was not until 1 863 that the micro-organ- 



