CHAPTER IV. 



THE BACTERIAL POISONS OF SOME OF THE INFECTIOUS 



DISEASES. 



We will now give our attention to the chemical poisons of some 

 of the infectious diseases, and in doing this we will illustrate, sub- 

 stantiate and extend the statements made in preceding chapters. 



Anthrax. — The definition of an infectious disease, as we have given 

 it, is illustrated by the facts which have been learned concerning 

 the causation of anthrax, which has probably been more thoroughly 

 studied than any other infectious disease. Kausch taught that this 

 disease has its origin in paralysis of the nerves of respiration, but as 

 to the cause of this paralysis he gave no information. Delafond 

 thought that anthrax has its origin in the influence of the chemical 

 composition of the soil affecting the food of animals and leading to 

 abnormal nutrition. The investigations of Gerlach, in 1845, demon- 

 strated the contagious nature of anthrax, which was emphasized by 

 Husinger in 1850 and accepted by Virchow in 1855. However, 

 as early as 1849 PoUender found numerous rod-like microorgan- 

 isms in the blood of animals sick with this disease, and his observa- 

 tion was confirmed by Brauell, who produced the disease in healthy 

 animals by inoculations with matter taken from an anthrax pustule. 

 Attempts were made to ridicule the idea that this organism might 

 be the cause of the disease but, in 1863, Davaine showed that these 

 rod-like bodies must have some causal relation to the disease, inas- 

 much as his experiments proved that inoculation into animals of the 

 blood of those sick with anthrax, produced the disease only when 

 taken at a time when the blood contained these organisms. He also 

 demonstrated beyond any question that these rod-like bodies are 

 bacteria, capable of growth and multiplication. The conclusions 

 of this investigator were combated by many; but Pasteur, Koch, 

 Bollinger, De Bary, and others studied the morphology and life 

 history of these organisms, and then came the brilliant results of 

 Pasteur in securing protection against inoculated anthrax by the vac- 

 cination of healthy animals with the modified germ and subsequent 

 inoculation with the virulent form. Then the question arose, How 

 do these bacilli produce anthrax ? and in answer to this question the 

 various theories which we have mentioned were proposed. 



In 1877, Pasteur filtered the blood of animals sick with anthrax, 

 also anthrax cultures, through porcelain and injected the germ-free 

 filtrate into animals without inducing the disease, and concluded 



48 



