334 BACTERIOLOGY. 



in the blood. Such an idea is hardly anything 

 more than a hasty conclusion ad hoc. In hab- 

 ituation to alcohol no " anti-alcoholin " is 

 formed, in habituation to morphine no " anti- 

 morphine," and yet a tolerance of these poisons 

 is established apparently by simple interven- 

 tion of the body-cells. The susceptibility of 

 the body to such poisons and the degree of pro- 

 tective action established, vary according to the 

 method of introducing the poisons, the period of 

 life and other influences. The degree of habitu- 

 ation to poison that may be acquired is also 

 very different according to the organs involved. 

 Schleich has accustomed animals to receive with 

 impunity large doses of chloroform, morphine 

 and cocaine, and yet the animals are never- 

 theless poisoned with slight dose's, when these 

 are introduced directly into the brain, just 

 as in Pasteur's method of inoculation in rabies. 

 The highest grades of poison tolerance show 

 indeed a definite dependence upon the method 

 by which the tolerance has been brought about. 

 This can signify, however, nothing less than 

 a direct dependence of these conditions of tol- 

 erance or immunity upon the cellular influ- 

 ences of the human body, and these influences 

 can certainly be brought to bear in the absence 

 of any specific anti-substances in the blood. 

 The poison tolerances belong in the same cate- 



