374 KATHARINE FOOT. 



by many investigators that germs are not transmitted by the 

 bite of the louse the sole method of transmission being infection 

 from their excrements. These are freely deposited on the skin 

 and in the clothing of the host and subsequent scratching of the 

 skin induced by the intense itching of the bites not only lacerates 

 the surface but frequently causes a deep wound that leaves a scar 

 lasting many months. It is self-evident that such lacerations 

 over surfaces more or less infested with the excrements of the 

 lice may cause a most effective inoculation. This method of 

 infection by the feces or the crushed body of the louse has been 

 demonstrated for typhus fever by Nicolle (1909), Nicolle, Conte 

 and Conseil (1910) and others. For recurrent fever by Sergent 

 and Foley (1910), Sergent, Gillot and Foley (1911), Nicolle, 

 Blaizot and Conseil (1912) and others. For trench fever, by 

 R. P. Strong (1918). Familiarity with the feeding habits of the 

 louse demonstrates the danger of this method of inoculation, for 

 the amount of excrement discharged by each louse is surprising. 

 I have frequently seen a single louse, during one hour's feeding, 

 discharge excrement ten times, and five times is not unusual. 

 For more than a year I have closely studied the feeding habits 

 of Pediculus vestimenti and in my report to the research depart- 

 ment of the Red Cross I described their behavior as follows: 

 "Observations made during the feeding hour demonstrate that 

 individual lice may behave very differently. As a rule they 

 bite at once when young and vigorous. Some become gorged 

 with blood in ten minutes and will not bite again, though most 

 frequently they bite several times during the hour, moving 

 around rather restlessly between times. Others bite continu- 

 ously the entire hour, casting their excrements while biting. 

 The old lice frequently do not bite for several minutes or even 

 half an hour and then suck the blood very deliberately." I am 

 inclined to believe that the method of biting demonstrated for 

 one hour indicates the method for the entire twenty-four hours 

 and that therefore the younger lice are almost continuously 

 feeding on the host, wandering about and biting very frequently. 1 

 This would accord with observations made by Miss Strobell and 



1 These observations support Nuttall's (1917) conclusions as to the probable 

 feeding habits of lice. He thinks they bite very frequently, for when raising them 

 on his wrist he noticed they started to bite at all times when he was quiet. 



