376 KATHARINE FOOT. 



only effect of the chiffon is to reduce the area of the skin exposed, 

 and the lice wander over the exposed area distributing the faeces 

 as usual. 



The danger of the louse as a promoter of disease has been so 

 long appreciated that he has claimed the attention of a large 

 number of investigators, the French and English forming the 

 majority. The work accomplished up to 1917 has been most 

 ably presented by Professor Nuttall, of Cambridge. His biblio- 

 graphical list is an index of the thoroughness of his historical 

 study of the subject. He has listed nearly 600 investigators. 



A second historical sketch was published in France the same 

 year (Soueges et du Noyer, 1917). These two studies are a 

 convenient record of all the historical data that can be of value 

 to the investigator. 



Two English investigators (Warburton, 1909, and Fantham, 

 1912) were the first to study the life history of Pediculus and 

 their results were supported and extended by Bacot in 1916. 

 He determined the number of moults to be three, the average 

 length of life of the louse, the average number of eggs deposited 

 daily by a single female and other details, all of which my investi- 

 gations support although our methods of work differed materially. 

 He used an entomological box containing a number of lice and 

 strapped this box on his person each night, allowing the lice to 

 bite from six to seven hours daily. My lice were fed only one 

 hour in the twenty-four and in such a manner that I could watch 

 them while feeding. 



The most serious difficulty in the investigation of lice is the 

 food supply. In all the accounts with which I am familiar the 

 investigator has had sufficient self-abnegation to feed his lice 

 on his own person, but not having reached those heights myself, 

 my initial difficulty was to find a host. There seems to be some- 

 thing extremely ridiculous in the mere suggestion of feeding a 

 louse, for my most serious and generous offers received the dis- 

 couraging response of a broad grin and an emphatic shake of the 

 head. I finally succeeded in securing a host at the Asile de 

 Nuit a night employee of that institution. He was an old 

 sailor whose evident familiarity with Pediculus at the Asile de 

 Nuit had led him to cease to regard them in a humorous light, 



