﻿STUDIES IN PLAGUE IMMUNITY. 



247 



§ oese "Pest Virulent;" on December 28 with 9 cultures of killed "Pest Virulent," 

 subcutaneously. On January 10, the animal was killed. The agglutination tested 

 in dilutions of 1 : 5, 1 : 10 and 1 : 20 were all negative after two hours. 



Monkey number 2720. — October 29, one agar culture "Pest Avirulent" injected 

 subcutaneously; on November 28, § oese "Pest Virulent" given subcutaneously; 

 on December 29, 1 oese of "Pest Virulent" given subcutaneously; on February 7 

 the animal was bled and the serum tested for agglutination. The serum of 

 monkey number 2G66 (see above) and of monkey number 3053 (normal serum) 

 were also both tested on this date with 72-hour cultures of "Pest Virulent" grown 

 in the ice box for six generations and with cultures grown for the same length 

 of time and for the same number of generations at 30° C. 



The results obtained are as follows: 



Table No. I. — Scrum of immune monkey number 2666 — Agglutination tests with cultures 

 grown for six generations in ice box and at 30° C. 



[The term "control" throughout the experiments signifies a suspension of the bacteria in saline 

 solution without the addition of serum.] 



GROWN IN ICE BOX. 



Dilutions. 



After li hours. 



After 16 hours. 



1:10 

 1:20 



IControl. 



(.Control. 



Negative _ 



Heavy precipitate. Fluid clear. 

 Do. 

 Do. 

 Do. 



do 



_.do ._ _ 



do 



GROWN AT 30° C. 



1:10 



1:20 

 (Control. 

 IControl. 



Negative 



Negative. Fluid not clear. Prac- 

 tically no precipitate. 

 Do. 

 Do. 

 Do. 



do _ 





_do 





Table No. II. — Serum of immune monkey number 2720 — Agglutination tests with cultures 

 grown for six generations in ice box and at 30° C. 



GROWN IN ICE BOX. 



Dilutions. 



After li hours. 



After 16 hours. 



1:10 

 1:20 



(Control. 



IControl. 



Negative .. 



_ _ do 



Heavy precipitate. Fluid almost clear. 

 Heavy precipitate. Fluid clear. 



Do. 



Do. 



do 



do 





GROWN AT 30° C. 



1:10 

 1:20 



f Control. 



IControl. 



Negative — 



do .- 



do .. 



Slight precipitate. Fluid not clear. 

 Negative. 



Do. 



Do. 



do - . 





