SPERMATOGENESIS OF PEDICULUS VESTIMENTI. 375 



myself on other species of Hemiptera, Euschistus variolarius, 

 E. serous, E. ictericus, etc., etc. These insects were fed on fruit 

 and could be closely observed during the twenty-four hours. 

 They fed almost continuously during the night as well as during 

 the day, and this leads me to surmise that the lice may feed with 

 equal frequency and explains the torment that soldiers suffer 

 even when infested with relatively few lice' and suggests the 

 possibility of inoculation from a single louse. 



The disputed question whether simply the bite of the louse 

 can inoculate the host has given rise to much discussion, some 

 investigators emphatically denying that any danger is caused 

 by the bite alone. Colonel Strong (1918) conducted some 

 experiments with the aim to determine this point and concludes 

 that "it seems fair to argue that the bite is probably a common 

 mode of infection." He states that in some instances the disease 

 was produced by pure biting experiments. His summary of the 

 probable methods of infection through biting is as follows: 



1. By piercing or stabbing and inoculating with mouth-parts 

 contaminated with infected material such as blood from the 

 patient or by louse faeces and body juices. 



2. By stabbing and inoculating from the skin which has been 

 contaminated with infected material such as louse faeces, and 

 possibly body juices. 



3. By stabbing and inoculating with mouth-parts which have 

 been contaminated with virus grown or developed in the stabber- 

 sac. 



4. By stabbing and regurgitating of the virus from the ali- 

 mentary canal. 



5. By stabbing and the injection of the virus contained in the 

 salivary juices. 



6. By hereditary infection. 



One of the difficulties in determining the value of the bite 

 alone is to eliminate the faeces from the experiment. Those 

 cases in which this is assumed to be done by allowing the louse 

 to bite through chiffon do not appear to me to be conclusive, 

 for in my experience they will not bite unless the chiffon is 

 pressed upon the surface with sufficient strength to force the 

 skin through the interstices of the chiffon, in which case the 



