MIGRATION OF BODY-LICE 85 



free on the body of a man who develops the 

 fever of one of the louse-borne diseases appeared 

 at once to be a most important question. These 

 lice have obtained the infecting feed of blood 

 either before the temperature has commenced to 

 rise or as it rises. If the rising temperature then 

 caused them to scatter, the spread of the disease 

 would be increasingly accelerated. 



Some of the soldiers under treatment at the 

 hospital and the civilians who were allowing us 

 to infect them with trench fever offered them- 

 selves for these exceedingly unpleasant experi- 

 ments, being willing to spend highly uncomfort- 

 able nights in the interests of science. The 

 experiments were carried out in a small room 

 with distempered walls and boarded floor. It 

 was not artificially heated, and the work was 

 done in February, when it was cold and raw. 

 A bed was made up on the floor of the room con- 

 sisting of two mattresses placed side by side and 

 covered by a white blanket, with ordinary pillows 

 and pillow-slips, and four white blankets to 

 cover the men. Into this bed the men, clad in 

 flannelette pyjamas, went in pairs, and two 

 hundred body-lice were released on the abdomen 

 of one of them in the region of the umbilicus. 

 The lice used were in each case adults and well- 

 grown nymphs, since young larvae might have 

 proved difficult to retrieve. The men were in- 

 structed not to get out of bed ; not to touch the 

 insects ; to avoid scratching if possible ; to inter- 



