56 SPECIFICITY OF RICKETTSIA PROWAZEKI 



Record of Guinea-pig 20, inoculated with rickettsia-infecied 



louse W 238 



The temperatures following the inoculation on May 15th 

 were as follows: 



F. F. 



May 15 102.4 May 24 103.5 



16 102.2 " 25 105.0 



17 102.0 " 26 104.7 



18 102.0 " 27 103.8 



19 102.4 " 28 103.4 



20 102.4 29 105.0 



21 101.5 30 104.1 



22 101.8 31 104.2 



23 102.0 



May 31st; killed. The autopsy was completely negative ex- 

 cept for a slightly enlarged spleen. 



The histological examination showed the lesions character- 

 istic of typhus in the brain. Two other guinea-pigs, Nos. 69 

 and 70, inoculated intraperitoneally with 2 c.c. of blood from 

 guinea-pig 20, remained with normal temperatures until June 

 14th when each developed temperature and ran a course typical 

 of typhus in the guinea-pig, of seven days duration in the case 

 of No. 69 and five days duration with No. 70. Following this 

 their temperatures remained normal for a further observation 

 period of nineteen and twenty-one days respectively. 



Result: Guinea-pig 20, inoculated with rickettsia-infected 

 louse W 238, developed typhus after an incubation period of 

 nine to ten days. The presence of typhus was proved by his- 

 tological examination and by subinoculations of two other 

 guinea-pigs. 



Conclusion: Rickettsia-infected louse W 238 contained the 

 virus of typhus. 



