100 BACTERIAL POISONS. 



when under the influence of the various secretions of the 

 body. Some bacteria are destroyed by a normal gastric 

 juice within a short time, while others are not. The con- 

 ditions of life and growth are different when the infecting 

 agent is introduced into the blood from what they are when 

 infection occurs by the way of the alimentary canal. This 

 is well recognized in the two forms of anthrax, one of which 

 arises from inoculation through a wound and the other by 

 way of the intestines. A preventive treatment which is 

 efficient in one is of no service in the other. Then, again, 

 we are to study those conditions of the blood and other 

 fluids of the body which are especially unfavorable to the 

 successful implantation or the continued existence of an 

 infectious disease. 



Thirdly, the chemical properties and the physiological 

 action of these poisons will demand careful attention. Some 

 are especially depressing in their action upon the heart, 

 others seem to manifest their chief energy upon the central 

 nervous system, while others still act like true gastro- 

 intestinal irritants. In the study of the toxicologic^l effects 

 of these bacterial .poisons every method of investigation 

 known in the most advanced physiological work must be 

 employed. The action of these agents on the heart, the 

 brain, the spinal cord, etc., must be thoroughly studied. 



