THE PRODUCTION OF ACTIVE IMMUNITY 143 



of time. In the first instance the protection afforded is 

 very temporary, while in the second it is still present even 

 after the lapse of from twenty-five to thirty days. It may 

 be possible that in the case of the injections extending over 

 a long period of time the immunity obtained is of a higher 

 degree. This is a point which will require further study. 



In the case of an animal which has been treated with- 

 the poisonous portion and has subsequently received a dose 

 of the living germ which would surely have proved fatal 

 for a normal animal, the symptoms noticed are identical 



Curve of normal animal inoculated with non-fatal dose of living bacillus. 

 Curve of immune animal inoculated with living bacillus. 



in every respect with those which follow the injection of a 

 non-lethal dose in an untreated animal. This is a very 

 important fact and one on which we have laid much stress. 

 Moreover, as can be seen from Fig. 8, the temperature 

 curve corresponds very closely with that obtained in the 

 case of a normal animal inoculated with a non-fatal dose 

 of the living colon bacillus. 



We see that in both instances there is no appreciable fall 

 in body temperature until from six to eight hours after 

 inoculation. At this time the minimum temperature has 



