﻿STUDIES IN PLAGUE IMMUNITY. 



215 



Series 24. — Inoculations with the strain "Maassen Alt" in monkeys. 



On December 4, thirty-two, 48-hour agar slant cultures of "Maassen Alt" were 

 suspended in 32 cubic centimeters of bouillon (1 cubic centimeter to each tube). 

 Monkeys numbered 1536 to 1547 inclusive were inoculated subcutaneously each 

 with 2 cubic centimeters of this suspension, equal to 2 agar cultures; monkeys num- 

 bered 1548 to 1552 inclusive with 1 cubic centimeter each and monkey number 1553 

 with a little less than \ cubic centimeter, equal to about I culture. Four of the 

 animals succumbed, apparently from the result of the vaccination. On December 

 18 the surviving ones were all reinoculated in the following manner: A 48-hour 

 agar slant culture of "Pest Virulent" (from guinea pig number 1516, second 

 transplant) was suspended in 5 cubic centimeters of bouillon, and each animal 

 inoculated subcutaneously on the opposite side of the body to that upon which 

 the first inoculation was given with 0.2 cubic centimeter, which equals a little less 

 than J oese of "Pest Virulent." Attention must be called to the fact that this series 

 was inoculated exactly the same as Series 23. Among the animals comprising the 

 present Series 24 there were also a number of large monkeys. For controls, the 

 same animals given as controls in Series 23 (see p. 191), numbered 1594 to 

 1605, were employed, all being inoculated in the same manner and on the same 

 day. It will be seen from the table that a number of the controls did not die 

 and hence conclusions regarding the exact value of the immunization in this 

 series can not be drawn. 



Animal 

 No. 



Vaccinated 

 December 4 

 subcutane- 

 ously with — 



Infected 



December 18 



with — 



Result. 



Autopsy and remarks. 



1536 



2 agar slant 





Dead Dec. 



Skin burned and incised at point of inocu- 

 lation revealing an abscess containing 





cultures, 





7, 3 days 





"Maassen 





after first 



pus in which numerous organisms are 





Alt." 





inocula- 

 tion. * 



present. Smears from spleen are nega- 

 tive. Cultures from the spleen devel- 

 oped one colony of Staphylococcus aureus. 

 Culture from abscess shows very numer- 

 ous colonies of Staphylococcus aureus 

 and also of "Maassen Alt." 



*1537 



do 





Dead Dec. 

 5, one day 



Cultures from the point of inoculation 

 show few colonies of "Maassen Alt" and 













after first 



of Staphylococcus aureus. Culture from 









inocula- 



the spleen negative. 









tion. * 





1538 



do 



Nearly J oese 

 "Pest Viru- 

 lent." 



Alive and 

 well. 





*It is not entirely clear that these animals succumbed to a pest infection alone. They were evi- 

 dently in poor health and in three the Staphylococcus aureus was also isolated. In the case of 

 monkey number 1552 it seems clear, however, that the animal really succumbed to pest infection. 

 It must be noted that animals numbered 1536, 1537 and 1547 died in a much shorter time than one 

 would expect from a pest infection with an avirulent organism. 



