76 BACTERIA. 



ism was supposed to have any definite relation to the fever. 

 Davaine, at that time stimulated by Pasteur's investigations 

 on the relation between micro-organisms and the butyric 

 fermentation, was led to suggest that these rods were, in all 

 probability, the actual and specific cause of the disease, which 

 suggestion, along with his observations on certain cases of 

 malignant pustule that were published in the following 

 year, may be looked upon as the first real attempt to 

 demonstrate the connection between the Bacillus anthracis 

 and the diseases known as malignant pustule and splenic 

 fever. Although he did not furnish rigorous proof of the 

 connection he was so far successful that, except for the 

 cultivation of organisms outside the body and the pro- 

 duction of the disease by means of the inoculation of pure 

 cultivations, work which Koch afterwards completed, 

 Davaine left no proof wanting. 



In the meantime, however, Delafond had demonstrated the 

 constant presence of the rodlets in the blood of animals affected 

 with splenic fever, and had also suggested their plant-like 

 nature. Davaine found that he was able to transmit the 

 disease to healthy animals by means of the inoculation of 

 blood that contained these rods ; whilst where the rods were 

 absent, although the blood might be exactly the same in 

 other respects so far as he was able to observe, he could not 

 produce the disease. He found that a single drop of diseased 

 blood contained from eight to ten millions of these forms, and 

 that by diluting the blood a million times, he was still able to 

 produce the disease by inoculation. Subsequent observers, 

 especially Leplat and Jaillard, objectingto his conclusions, said 

 that similar rods had been found in other diseases. They 

 pointed out that other elements in the blood — an extremely 

 complex fluid — might be the cause of the infective disease, and 

 that the rodlets themselves might be only an accidental factor. 

 Leaving this safe ground, however, their further criticisms 

 were based on the supposition that all the rod-shaped bodies 

 were identical in structure and life history, and that conse- 

 quently they should have the same effect when introduced 

 into the body, and they concluded that because similar 

 organisms taken from vegetable infusions did not produce 

 anthrax, that therefore the rodlets in the blood could not be 

 the specific infective agent. Davaine's answer was that their 

 contradiction of his statements was due entirely to misconcep- 



