THE PRODUCTION OF ACTIVE IMMUNITY 159 



Protocol, Weight, Interval, Amount given, 



No. gin. days. c.c. Result. 



330 460 1 5.0 Recovery 



331 300 3 5.0 Death 



332 225 7 5.0 Death 



333 290 9 2.5 Recovery 



334 235 11 2.0 Death 



335 360 14 1.0 Recovery 



Comparing Tables XV and XVI, it will be seen that the 

 immunity given by 25 mg. of the residue, although it may 

 be as great as that given by 50 mg. at the end of the first 

 twenty-four hours, declines more rapidly and is less at the 

 end of three days, and continues to be less at eleven days. 

 The only element of doubt that we can see in these con- 

 clusions lies in the small size of all the animals, save No. 1 

 used in Table XVI. However, we have not found that size 

 or weight of guinea-pigs are important factors, provided, 

 of course, that the animals are in good condition, in influ- 

 encing the result after inoculation with the colon or the 

 typhoid bacillus. 



TABLE XVII 



These animals had from two to three treatments, receiving 

 each time 50 mg. of the residue. These treatments were 

 at intervals of three days. The protocol number, the weight 

 of the animals, the number of treatments, the total amount 

 of residue given, the interval in days between the last 

 treatment and the inoculation, the amount of the culture 

 twenty-four hours old, and the result are given: 



Result. 

 Recovery 

 Recovery 

 Recovery 

 Recovery 

 Recovery 

 Recovery 

 Recovery 

 Recovery 

 Recovery 

 Recovery 

 Recovery 

 Recovery 

 Recovery 

 Recovery 



