MIGRATION OF BODY-LICE 87 



into which they might have obtained access. 

 In this way complete data of the migrations of 

 the lice were obtained. Six of these experiments 

 were carried out, in three of which the man upon 

 whom the lice were released, called the primary 

 host, was febrile, and in three he was normal. 

 His bed-fellow, the secondary host, was normal 

 in each case. The febrile men were in each case 

 suffering from trench fever. 



The details of these experiments are given 

 below. The exact distribution of the lice is not 

 included, to avoid laborious detail. The numbers 

 of the lice in the various positions are given in 

 percentages of the numbers recovered. Those 

 marked "on or about " the host are the ones 

 which were on the body, inside and outside the 

 pyjamas, and on the inner side of the blankets 

 immediately against the men. These also in- 

 clude the small numbers which were on the pillows 

 and between the upper blankets. The lice were 

 assigned to the man to whom they were nearer. 

 Those marked " inside the pyjamas " include the 

 few which were found on the body, an average 

 of less than 1 per cent in the twelve cases, and 

 the ones which were clinging to the garments 

 on the inner side. In one or two cases the men 

 wore undervests, and the lice upon them were 

 included in the count of those inside the pyjamas, 

 without any reference as to which garment 

 harboured them. These results are summarised 

 in the Table, in which are also included the 



