MORPHOLOGY 139 



Rickettsia were never found by us free in the body cavity 

 (coelom) of the louse, a noteworthy fact because during diges- 

 tion pseudopodia project from the epithelial cells of the gut for 

 a distance equal to half the length of the cell into the body 

 cavity. 



The feces from fourteen of the experimental louse boxes 

 were examined for rickettsia. The organisms were found in 

 the feces from four boxes only which contained many lice 

 heavily infected with Rickettsia prowazeki. Infection of the 

 feces was expected since the examination of louse sections 

 had constantly revealed the presence of rickettsia free in the 

 gut lumen. A series of twelve guinea-pigs was inoculated with 

 feces known to be heavily infected with Rickettsia prowazeki. 

 From temperature reactions it is believed that in five instances 

 the animals inoculated contracted typhus; the presumption 

 of typhus, in these experiments, is based solely on the tempera- 

 ture reactions and is not confirmed by histological examina- 

 tion of tissues. 



Da Rocha-Lima (1919, p. 242) did not succeed in infecting 

 guinea-pigs in two experiments with louse feces which had 

 been dried for twenty-four hours at room temperature (22 C.). 

 On the other hand Nicolle, Blanc, and Conseil (1914) did infect 

 guinea-pigs with louse feces. In our experiments we did not 

 intentionally dry the louse feces which were used for the in- 

 jection of guinea-pigs and it is probable that some of the 

 material was not thoroughly dry, although the lice had not 

 been fed within twenty-four hours. 



Ova, larvae, and nymphs from eight boxes which contained 

 lice infected with Rickettsia prowazeki were examined in smear 

 preparations. Rickettsia were found in no instances. 



Curious, long, thick, densely staining red filamentous bodies 

 (Fig. 16, plate III) were seen in the gut cells of four rickettsia 

 infected lice from two experimental boxes. They exhibit no 

 internal structure and some of them terminate in bulbous 

 extremities. They are illustrated in Figs 7a and 7b, plate II. 

 They are of varying diameters and of considerable length, so 

 that it is necessary to follow them through several successive 



