102 
Biology of Pediculus humanus 
( b) Corporis. (Lot 212.) 
Apparatus as before. All the insects had gorged 6| hours before 
and still contained a considerable amount of food; they were trans¬ 
ferred directly from the thermostat at 30° C. They climbed so slowly 
that only one was allowed to climb 20 cm. The distance actually 
travelled is stated, but, for comparison with capitis, the rate of progress 
is given as for 20 cm. 
Actual distance 
Temp. Stage 
Time 
No. of hairs Direction travelled in cm. 
00 
O 
O 
HO 
, 5' 54" 
2 
vertically upward 20 
• l? 
8' 12" 
1 
„ „ » io 
d 
12' 42" 
1 
10 
3rd st. 
L. 11'6" 
1 
„ „ 10 
2nd st. L. 14' 
1 
„ „ 10 
fd 
15' 48" 
1 
horizontally (unfed) 10 
10' 54" 
1 
‘ (fed) 10 
3rd st. L. 11'16" 
1 
10 
2nd st. 
L. 11'34" 
1 
„ s io 
When the apparatus was placed in 
the (glazed) thermostat at 30° C., 
the same insects made better 
records 
. The experiments demonstrate 
the effect of temperature on their activity, and they now climbed the 
full 20 cm. 
Temp. 
Stage 
Time 
No. of hairs Direction 
30° C. 
cj unfed 
2' 13" 
2 vertically upward 
1 1 
f$ „ 
4' 15" 
2 
1 
l? „ 
5' 56" 
1 
J 
f 9 gorged 
2' 40" 
2 
1 
19 „ 
5' 43" 
1 
J 
I'd „ 
2' 21" 
2 
" 99 99 
1 
id „ 
r 54" 
1 77 77 
J 
C $ unfed 
6' 16" 
2 horizontally 
1 
19 „ 
5' 30" 
1 
d „ 
8'9" 
2 
d 
7' 18" 
1 
Whilst at first 
sight these 
observations may appear trivial, they 
really afford striking objective evidence of the relative activity of 
capitis and corporis under like conditions, and of the influence of tem¬ 
perature on the agility of lice as evidenced in corporis. 
The ease with which capitis clings, and the speed with which it 
travels upward along a single hair, indicates sufficiently how girls with 
1 Tlie brackets denote records relating to the same individual. 
