380 KATHARINE FOOT. 



As the female had her third moult between the i8th and 

 igth of August, she lived only 28 days after maturity, less than 

 the average length of life for a female; but other females in the 

 laboratory kept under the same conditions lived 42 days, 40 days, 

 39 days, etc. Bacot found the average length of life of a female 

 to be 34 days. If my lice are a little below this average I think 

 it is probably due to the difference in feeding he fed his lice 

 six or seven hours daily and mine were fed only one hour daily. 



According to my experience, the longer a race is bred in the 

 laboratory the less prolific they become and the death rate is 

 much higher. I believe this is due entirely to an abnormal lack 

 of nourishment. Feeding only one hour in twenty-four is 

 certainly very abnormal for these insects. 



One cannot study the record of the large amount of experi- 

 mental work done on the louse without being impressed with the 

 need of feeding these insects apart from the human host before 

 certain problems now in dispute can be solved. My efforts have 

 been largely given to this well high hopeless task which is my 

 apology for a very superficial study of the spermatogenesis. 



PAPERS REFERRED TO. 



Bacot, A. 



'16 Notes on Pediculus humanus and Pediculus capitis. Brit. Med. Journ. 

 Foot, Katharine and E. C. Strobell. 



'14 The Chromosomes of Euschistus variolarius, Enschistus servus and the 



Hybrids of the Fi and Fz generations. Arch. fur. Zellf., Bd. 12. 

 Langeron, M. 



'16 Precis de Microscopic. Masson & Cie, Editeurs, Paris. 

 Nicolle, C. 



'09 Reproduction experimental du typhus exanthematique chez le singe. 



C. R. Acad. des Sc., 149. 

 Nicolle, C., Conte and Conseil, E. 



'10 Transmission experimental du typhus exanthematique par le pou du corps. 



Ann. Inst. Past., 24. 

 Nicolle, C., Blaizot, L. et Conseil, E. 



'12 Etiologie de la fievre recurrente. Son mode de transmission par le pou. 



C. R. Acad. des Sc., 154. 

 Nuttall, George. 



'17 Bibliography of Pediculus and Phthirus. The Part played by Pediculus 



humanus in the Causation of Disease. Parasitology, Vol. X. 

 Sergent, E. and Foley, H. 



'10 Recherche sur la fievre recurrente et son mode de transmission dans une 

 epidemic algerienne. Ann. Inst. Past., 24. 



