NATURAL RESISTANCE 171 



Since, as postulated in the previous chapter, it ap- 

 pears that cytost is concerned in muscular fatigue, 

 Weichardt's fatigue antiserum may be closely re- 

 lated to or identical with anticytost. In view of our 

 present knowledge, however, it appears more likely 

 that more convincing experimental results can be ob- 

 tained by active immunization with homologous cy- 

 tost than by the transmission of antibodies elaborated 

 in another animal. In consequence, in the majority of 

 the experiments to be discussed subsequently, the 

 various animals used were immunized actively rather 

 than passively. 



From the standpoint of general biology, the im- 

 munization to shock discussed above is of importance 

 only in so far as it demonstrates our ability to raise 

 an animal's resistance to the effects of high concentra- 

 tions of cytost. From a general standpoint this is of 

 interest because, as we have shown, various bodily 

 activities as well as injuries lead to a liberation of 

 this endogenous tissue product. 



If, as postulated previously, an Increased tolerance 

 to cytost is a factor in an animal's natural resistance, 

 then we should expect that actively immunized ani- 

 mals would recover from minor injuries more rapidly 

 than non-immunized. In order to test this concept, 

 the rate of healing of standardized wounds was com- 

 pared in immunized and non-immunized cats. For 

 this purpose an area back of the heads of the animals 

 was shaved, and, under ether anesthesia, a triangular 

 flap of skin was removed between the occipital tuber- 

 osity and withers. As far as possible, these injuries 

 were made alike, the dimensions of the triangles being 

 held to a standard size. The rate of wound healing 



