188 
Notes on Head- and Body-Lice, etc. 
it to a remarkable display of activity. It moves in the general direction 
of the tube, and in doing so displays a frantic eagerness of movement 
which is not only amusing but quite foreign to its ordinary method of loco¬ 
motion. If the tube is brought near a louse which is in the act of feeding, 
it may show some excitement, but does not ordinarily relinquish its hold. 
The reaction has a certain practical value as affording a means of 
greatly facilitating the removal of lice from the body, more particularly 
in the case of head-lice, whose removal from the hair generally entails 
a good deal of trouble. 
If a comb, warmed enough to be pleasantly hot to the hand, be 
used, the lice become much excited and are as it were tempted into the 
open instead of sticking to their dug-outs among the bases of the hairs. 
The comb thus gets free play among them, and they are removed with 
a very marked economy of time and trouble. I have had hearty testi¬ 
monials to the value of this method of dealing with an insect which is 
especially troublesome in India. 
The temperature-reaction of Plithirus pubis, as tested by the 
hot tube, seems to be essentially similar to that of Pediculus. When 
feeding they are generally little affected, but at other times become 
greatly excited and move with remarkable eagerness and rapidity. If the 
hot tube be brought near a Plxtliirus laid on its back on the table, the 
insect’s wild efforts to reach it attain an intensity which is almost pathetic. 
How far this reaction of lice can be considered as parallel to that of 
female mosquitoes I have not tried to ascertain. In both cases a hot body 
has a markedly stimulating effect; in mosquitoes it results in a general 
excitement and marked eagerness to bite; in lice it certainly results 
in rapid and excited movement, and this would be of advantage to the 
insect in securing the wider distribution of the species by infecting 
anyone whose body came in contact with that of their host. It may 
be worth noting that I have recently tried the effect of placing half-a- 
dozen lice on the hairy part of the fore-arm and then laying over them 
the corresponding part of the other arm. Four trials were made, and in 
each case one or more lice were found to have been transferred after the 
arms had been in contact for periods varying between 15 and 30 seconds. 
Dispersal may very possibly be the only advantage accruing from the 
reaction, but on the other hand there might also exist some connection 
between the act of blood-sucking and the temperature of the surface. 
I have not observed it, but if such a connection exists, its demonstration 
would probably require experiments much more careful than the 
rough observations referred to in this paper. 
