KATHARINE FOOT. 



menti and suffered greatly from the infestation. Du R. says he 

 was never attacked at any time during that period and later he 

 slept for two weeks between two soldiers who were infested and 

 the lice were also in the blankets. During those two weeks he 

 had no lice whatever, though he frequently searched for them. 

 He kindly consented to allow me to experiment with his case and 

 July 19, 1919, I took three young lice to Soissons for a prelimi- 

 nary test. My aim was to determine whether their behavior 

 showed any abnormal features while they were on Du R.'s skin. 

 At nine p.m. they were fed on a normal host and at ten p.m. 

 they were placed on Du R.'s arm. Feeding one hour before the 

 test eliminated the factor of intense hunger which might force 

 them to bite a possibly distasteful host. 



Result. I could detect no abnormal features in the feeding. 

 They bit almost at once and each fed at least twice during the 

 fifteen minutes they were on Du R.'s arm. They were not rest- 

 less, made no effort to escape, and were not combative. 



Later this experiment was continued to determine whether the 

 lice are not normally nourished by Du R.'s blood, whether biting 

 is followed by itching, and whether selecting various areas on 

 the arm would show that Du R.'s skin is abnormally thick. In 

 my experience lice cannot feed where the skin is callous, for ex- 

 ample, the distal end of the thumb or various places on the palm 

 of the hand. 



One naturally suspects that at least some cases of so-called im- 

 munity may be due solely to the fact that biting is not followed 

 by itching. A case in point is that of a friend whose maid was 

 infested with fleas, and Madame de B. expressed surprise that 

 they had not attacked her also. Her maid replied " Madame is 

 mistaken, for I found twelve on her underwear." This led to 

 the discovery that she was bitten without being poisoned. 



The following September, Sergeant Du R. came to the labora- 

 tory one hour daily for ten consecutive days and the lice were 

 fed on various parts of his arm from the wrist to the shoulder. 

 Those that died were dissected and their sex noted. 



It was hoped these further experiments would conclusively 

 answer the above mentioned three questions : 

 First Is Du R.'s blood injurious to lice? 



