MIGRATION OF BODY-LICE 89 



will be seen that the successive points on the 

 curves represent the relative distance of the 

 migration of the various numbers. 



SERIES A. In which both the Primary (P.H.) 

 and Secondary Hosts (S.H.) were afebrile. 



Experiment 1. 



Temperatures of P.H. : 98-4-97-8. Skin normal. 

 Temperatures of S.H. : -98-3-98-4. Skin normal. 



The lice were released at 8 P.M., having been last fed 

 five to eight hours previously. They were watched for 

 about half an hour, during which time most of them fed 

 but they did not scatter. In the third hour about 

 twelve had crept outside the pyjamas of P.H., while 

 the majority were still in the original position. S.H. 

 had not felt any on him. In the fifth hour the lice had 

 nearly all left the original site, a few being outside the 

 pyjamas of P.H., who said he had felt them wandering 

 all over his back. S.H. had felt none. In the thirteenth 

 hour P.H. said he had felt them all over him all night 

 and had slept little. S.H. had slept well and did not 

 know he had been bitten till he awoke at dawn. He 

 then felt them walking on his legs and was bitten there. 

 In the sixteenth hour after the commencement the lice 

 were collected, with the following result : 



184 = 92 per cent of the 200 lice were recovered. Of these, 

 121 =65-7 per cent were on or about P.H. ; 

 . 63 = 34-2 per cent were on or about S.H. ; 



70 = 38-0 per cent were inside the pyjamas of P.H. ; 



36 = 19-5 per cent were inside the pyjamas of S.H. 



Experiment 2. 



Temperatures of P.H. : 97-l-98-2. Sweated a 



little in the night. 

 Temperatures of S.H. : 98-4-97-6. Skin normal. 



The lice were released at 7.30 P.M., having been fed 



