214 
Biology of Pediculus human us 
described on p. 216.) Of the seven adults raised on white four were pale, 
two very slightly and one slightly pigmented. But two adults were raised on 
black, one was dark and the other pale, the larvae that died whilst being raised 
were frequently darkly pigmented. The heat absorption by the black affected 
the insects adversely. 
Experiment XI (different colours). 
On 10. viii. 18, second and third stage larvae of the foregoing strain of lice 
were removed from an overstocked breeding box which contained white 
flannel that the insects had soiled. It was noticed that many larvae were 
darkly pigmented and this was attributed to (1) the lice being crowded, and 
(2) the box being soiled. These larvae were distributed in differently coloured 
boxes (tabulated below) and fed twice daily. The boxes were opened once 
every 24 hours to remove any adults that had moulted, these insects being 
isolated in boxes of corresponding colours for 24 hours at 31° C., thus giving 
them plenty of time to darken. The following results were recorded in respect 
to pigmentation: 
Colour 
of box 
August 
12 
13 
14 
15 
16 
17—18 
19 
violet 
• 
• 
1 
• ••• 
3 
• ••• 
4 
• •••• 
1 
• ••• 
• 
1 
o 
* 
indigo 
1 •• 
1 • 
1 
• •••• 
1 
• ••• 
2 
• •••• 
• 
• 
1 
• •• 
3 
• •• 
blue 
• 
• 
2 
• ••• 
1 
• •• 
1 
• ••• 
• 
1 
• •• 
1 
• • 
1 
• it 
green 
• 
• 
1 
• 
2 
• • 
1 
• • 
• 
• 
1 
o 
2 
oo 
1 
• 
2 
O 
orange 
• 
• 
2 
• • 
1 
• ••• 
• 
• 
• 
1 
• 
2 
• • 
1 
o 
1 
o 
black 
• 
• 
• 
• 
1 
• •• 
2 
• ••• 
2 
1 
• 
1 
• •• 
1 
• • 
1 
• 
Summing up the results, the different boxes yielded: 
violet 10 (7<?,3$) 4*### 
5 •••• 
1 O 
indigo 10 (4<£,6$) 3 •••• 
1 •••• 
4 • •• 
1 •• 
1 O 
blue 7 (4 <?, 3 ?) 
3 •••• 
3 ••• 
1 •• 
