72 SPECIFICITY OF RICKETTSIA PROWAZEKI 



the usual period of a typhus infection and incubation period, so 

 that we must accept the temperatures of guinea-pig 8 as rather 

 indicative of typhus than otherwise. The short temperature 

 rise on July 3, 4, and 5 coincided with very hot weather in 

 transport in a. freight car when many guinea-pigs showed 

 elevated temperatures. 



Result: Guinea-pig 8, inoculated with louse W 214, ap- 

 parently free of rickettsia, developed typhus fever. That the 

 infection was typhus was shown by the failure to react typically 

 following inoculation with human blood of proved infectivity. 

 (The brain of this guinea-pig, and those of others killed upon the 

 same date, were lost. Hence there is no histological control.) 



Conclusion: Louse W 214, a preparation of which contained 

 no rickettsia, probably contained the virus of typhus. 



Record of Guinea-pig 18, inoculated with the viscera of 

 rickettsia-free louse (nymph) W 215 



The temperatures following the inoculation on May 15th 

 were as follows: 



May 15 101.9 May 24 102*.3 



16 102.6 25 102.9 



17 102.9 26 104.3 



18 102.4 27 103.8 



" 19 102.8 28 104.0 



" 20 ;... 102.8 29 104.0 



21 103.6 30 104.1 



22 102.7 31 104.0 



23 101.8 



May 31st; killed. The autopsy showed an enlarged spleen 

 covered with a thin transparent fibrin-like layer. All other tis- 

 sues were negative. 



On histological examination the lesions characteristic of 

 typhus were found. 



Result: Guinea-pig 18, inoculated with the viscera of louse 

 W 215, a preparation of which contained no rickettsia, de- 

 veloped typhus, which was proved by histological examination. 



Conclusion: Louse W 215 (nymph), in a preparation of 

 which no rickettsia were found, contained the virus of typhus. 



