IMMUNITY. 349 



tion to their poisons, are often deceptive, if we 

 fail to consider sufficiently the method of in- 

 troduction or inoculation. A state of protection 

 against infection by way of the skin may be 

 present in cases where immunity does not exist 

 at all to infection by way of the blood or brain ; 

 it may be present for one side of the body or for 

 one extremity and be lacking in other regions. 

 If this fact is forgotten then it may appear as 

 if the influence of the body-fluids were pre- 

 eminent, when in reality the last word rests 

 with the body-cells. On this basis Schleich 

 has very happily attempted to explain why 

 diseases like diphtheria, that start from the 

 mucous membrane of the throat, or that start 

 from the lungs, like pneumonia and influenza, 

 or from the intestines, like cholera, confer 

 upon the organism little or no immunity from 

 another attack ; it is because large tracts of 

 cells remain exempt from the effects of the 

 first invasion and therefore acquire no protec- 

 tion. It seems as if perhaps toxic properties 

 did not exist, when in reality toxic manifesta- 

 tions are prevented only by chance. The al- 

 legedly non-poisonous diphtheria serum itself, 

 when introduced into the derma, shows a toxic 

 action which manifests itself in pains and in 

 swellings of the joints and in the form of pe- 

 culiar and obstinate skin affections at times 



