II 



TECHNIC 



1. THE LOUSE STOCKS 



THE securing of stocks of lice free from demonstrable micro- 

 organisms of any sort and beyond question free from the virus 

 of any disease was of supreme importance. To ensure such a 

 stock of lice, nits were obtained from a patient attending 

 the Out-door Department of the Montreal General Hospital. 

 These nits were hatched out on members of the expedition, 

 Todd and Wolbach, and separate strains were maintained by 

 each, known as the T and W strains. As may be seen in Table I 

 (p. 7) the lice of these American stocks remained free from 

 invasive micro-organisms of all types during the entire investi- 

 gation. 



A second stock of uninfected lice was brought by Mr. Bacot. 

 These lice had been under observation and had been nurtured 

 by Mr. Bacot since November, 1915. Lice from this stock were 

 used for most of the trench fever researches by British and 

 American commissions (Bacot, 1921, p. 156), and were proved 

 to have been free from rickettsia-like organisms for over a 

 period of two years prior to our research. Many lice from Mr. 

 Bacot 's stocks carried large gram-negative cocco-bacilli in the 

 vagina and uterus or upon the surfaces of the copulatory ap- 

 paratus of the male (folds of the vesica penis). Rarely, similar 

 bacilli were encountered in the posterior portion of the alimen- 

 tary tract. The uniform absence of bacteria from the intestinal 

 canal of all lice is striking. These, or similar bacteria, were 

 found in the uterus and vagina of but one female of the Ameri- 

 can stock. (See Arkwright and Bacot, "A Bacillary Infection 

 of the Copulatory Apparatus of Pediculus humanus" Para- 

 sitology, Vol. 13, No. 1, 1921, p. 25.) 



Nearly the whole of the experimental work of the Commis- 

 sion was done with lice of the American stock, as early in the 



5 



