INTRODUCTION 



THE general purposes of the Commission were to make etiolog- 

 ical and pathological studies upon typhus. 



The determination of the exact nature of the specific cause of 

 the disease was held as the most important goal. A minute 

 histo-pathological study was held to be an essential require- 

 ment for the understanding of typhus as a disease, and par- 

 ticularly for appraising relationships between lesions found and 

 presumptive etiological agents which might be encountered. 

 Bacteriological methods were deliberately given second im- 

 portance, pending the development of indications during the 

 research. 



The transmission of typhus by the body or clothes louse was 

 accepted as proved. The first information to be obtained was 

 the nature of the demonstrable micro-organisms acquired by 

 lice nurtured upon typhus patients. Subsequent work was to 

 be directed towards the identification of a micro-organism in 

 constant association with typhus in lice and finally, if possible, 

 to prove by experimental means the identity of this micro- 

 organism and the virus of typhus. Other evidence was to be 

 sought for in the demonstration of micro-organisms in lesions 

 specific for typhus and experience in Mexico (Wolbach and 

 Todd, 1920) gave promise of success in this direction. At- 

 tempts at cultivation were to be deferred until we became con- 

 vinced that strong proof was at hand in favor of a definite 

 micro-organism being the cause of typhus. 



The volume of work necessitated by the carrying out of this 

 program on a sufficiently large scale, and the limited time at 

 our disposal, made it impossible to attempt extensive serolog- 

 ical or cultural observations. Nevertheless, thirteen unsuc- 

 cessful attempts were made to cultivate the bacillus described 

 by Plotz, Olitsky, and Baehr (1915), (see p. 113); and the 



3 



