THEORIES OF IMMUNITY. 



nently by means of " soluble " toxines are mem- 

 bers of the first group. 



The second group of bacterial diseases, how- 

 ever, is a most important one, and in it there is 

 seen no such production of separate and soluble 

 toxines. In the bacteria concerned, the filtrates 

 of bouillon cultures have little — or absolutely no 

 — poisonous properties, and the effects in the 

 diseases produced by them are more or less di- 

 rectly connected with the bacterial cell itself. 

 These diseases are the result of the growth of 

 bacteria, which if they act by the production of 

 toxines at all do so by what are called " intra- 

 cellular toxines." These substances are inti- 

 mately connected with the bacterial protoplasm 

 and cannot be separated from it, or if they are, 

 only with very great difficulty. Pneumonia, the 

 septicemias, typhoid fever, cholera, plague, and 

 tuberculosis (as a chronic disease) are examples of 

 this form of bacterial action. The general char- 

 acteristics of all diseases of this type are fever as 

 a general manifestation, and of inflammation as a 

 sign of the local presence of the bacteria. In 

 the bacteria producing results of this general 



43 



