2/0 PHYSIOLOGICAL CHEMISTRY. 



ally an antihemolysin which works to prevent further destruc- 

 tion of the rabbit corpuscles. But the action does not stop 

 here. By injection of blood, hemolysins for the corpuscles of 

 this blood are also formed. Numerous experiments of this 

 kind have been made with animals. For example, when rab- 

 bit's blood is gradually injected into the dog the production of 

 hemolysins is stimulated and the serum of the dog so treated 

 is found to be far more toxic for the rabbit than was the orig- 

 inal serum. This toxic action, by test-tube experiments, has 

 been found to be parallel to the hemolytic action of the dog 

 serum on the rabbit corpuscles, thus showing that the toxicity 

 may depend on the destruction of the corpuscles. The hemo- 

 lysins produced as just explained are also in general specific in 

 their character, which can be followed by experiments in vitro 

 as well as in corpore. 



In general the bactericidal action of serum resembles its 

 hemolytic action, although control experiments in vitro can- 

 not be as readily performed. We have therefore the bacteri- 

 olysins to consider along with the other cell destroyers. These 

 bodies exist to some extent in normal blood and other body 

 fluids and serve to protect the organism against the attack of 

 bacteria which in any way gain admission to the body. Milk 

 is relatively rich in bacteriolysins and hence the well-known 

 germicidal action which has been long recognized. In this 

 respect the behavior of mother's milk is more marked than that 

 of cow's milk. Besides the cytotoxins of this class normally 

 present in blood, specific bodies may be developed by the gen- 

 eral methods followed in other cases, that is by the gradual 

 introduction of cultures of specific bacteria, beginning with 

 cultures of relatively little virulence. In this way the blood 

 of the treated animal becomes immune for some one bacterium 

 species and develops the power of destroying that bacterium 

 only for which it was specially immunized. The same animal 

 may be immunized against several kinds of bacteria at the 

 same time and the different specific bacteriolysins do not ap- 

 pear to have any destructive action on each other. They exist 



