A. Bacot 
235 
Cold. Active lice in all stages were placed in a cloth-lined box and 
kept in a cold room at — 2-3° to — 1*1° C. for 48 hours; all were stiff 
and motionless when taken out, but after 24 hours in a vest pocket all 
revived; they were afforded ample opportunity of feeding, after which 
they were again kept in the cold room for seven days; all were dead 
on femoval. 
Feeding. Hungry lice do not as a rule wander, but settle down to 
feed at once if placed on a suitable skin area. When a number are 
placed on a small area of not more than a sqiiare inch, there is a con¬ 
siderable difference in the time taken to draw blood; many obtain it 
within half a minute to a minute, others within two or three minutes, 
while a few may be five minutes or over. Such delay seldom if ever 
occurs with bugs {Cimex leclularius) presumably owing to their more 
powerful pumping apparatus, or possibly the greater depth of the 
wound. Fleas not infrequently fail at the first attempt, in which case 
they usually shift and try again at another spot. Lice, however, 
rarely if ever shift, but wait patiently until, presumably, the irritation 
caused by the injection of saliva dilates the capillaries and brings the 
flow of blood to the wound. This reliance upon the salivary fluid fits 
in well with the fact of the more intense and lasting effect of the bite, 
as compared with that of either fleas or bugs (on the author). With 
insects having such a generally restricted range of operations there is a 
very fair chance of their feeding a second time on the same area and 
benefiting by the inflammation resulting from their previous attacks. 
Experiment shows that there is much the same variation in the 
time required to obtain blood on the part of newly hatched larvae 
as with larvae in their second skin, nymphs and adults; and the speed 
with which they fill their crops also varies from about two to fifteen 
minutes. 
Growth and moulting: Pediculus humanus (vestimenti). 
Forty newly hatched lice were kept in a box in a vest pocket and 
afforded opportunity for feeding during six or seven hours each 
night; cast skins were found as under: 
Number of days after hatching 
'^1 2 3 4 5 6 7 8 9 10 11 12 13 m'' 
Number of 
cast skins 1 17 22 
1st moult 
3% 42% 55% 
() 
2 !) 
1 
22 13 
2nd moult 3rd moult 
15% 72% 13% 5% 3% 55% 32% 5% 
16 
Parasitology ax 
