112 SPECIFICITY OF RICKETTSIA PROWAZEKI 



CONCLUSIONS 



The presence of Rickettsia prowazeki in lice in our experience 

 is proof of the presence of the virus of typhus. 



A variable percentage only of lice nurtured upon typhus 

 patients acquire the virus of typhus; and this holds true in 

 boxes where all lice have equal opportunities to become 

 infected. 



After allowing for the technical difficulties in making ade- 

 quate search for rickettsia and injections from the same louse 

 and for the uncertainty of the reaction of guinea-pigs to typhus 

 blood in the control inoculations in the test for immunity, we 

 believe that the data from the above experiments are sufficient 

 proof that the virus of typhus and Rickettsia prowazeki are 

 inseparable. 



