ACTION ON ANIMALS 123 



it may be stated that they are similar in all respects to 

 those induced by the living bacillus. The temperature 

 remains the same or may rise slightly during the first two 

 hours. At the end of the four hours it has begun to fall, 

 and there is a decided drop from then on until the time of 

 death, provided the dose given is a fatal one. If a non-fatal 

 dose has been injected intraperitoneally the temperature, 

 as will be seen from Fig. 6, has reached a minimum at the 

 end of from six to eight hours and has returned to normal 

 again in from twelve to twenty hours. 



Moreover, as a general rule, it may be stated that the 

 fall in non-fatal cases seems to be directly proportional to 

 the amount of bacterial substance injected. That this 

 should be the case seems to be only natural when we con- 

 sider the fact that in this instance we have largely done 

 away with that factor which is known as the individual 

 resistance of the animal. As has been previously mentioned 

 in the case of the living bacillus, the individual resistance 

 plays an important part in determining the amount of 

 poison which will ultimately be set free in the body. For 

 example, whereas 1 c.c. of a twelve-hour culture of our 

 colon bacillus invariably proved fatal, 0.25 c.c. never did. 

 The explanation of this is to be found in the fact that with 

 the smaller dose all animals were able to cause disintegra- 

 tion of all bacilli injected before a fatal dose of poison was 

 set free. If now 0.5 c.c. be given some would recover, while 

 others would die. In this case we would speak of the former 

 as possessing a greater individual resistance than the latter. 

 This simply means that, in the first instance the animal 

 has possessed a sufficient quantity of bactericidal substance 

 directly available to cause disintegration of all bacilli before 

 the latter have multiplied to a sufficient extent to furnish 

 enough poison to kill the animal on its liberation. . On the 

 other hand, those animals which succumbed did not possess 

 quite enough of the bactericidal substance, or at least did 

 not possess it in a form available for immediate use. When, 

 however, the dead bacterial substance is given the dose 

 of poison which the animal receives is a certain definite 

 amount and is not capable of subsequent increase. 



