G. H. F. Nuttall 
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B. Boxes with fenestra undermost (partial darkness). 
(/) Black box, contained 25 eggs laid 25-26. vi. 18. Hatching began 2. vi., 
and 7 adults emerged 11-13. vi. Examined 4-6 days after moulting, 6 of the 
adults appeared dark and 2 moderately pigmented. 
(g) White box, contained 30 eggs laid 26-27. vi. 18. Hatching began 2. vi., 
and 11 adults emerged 11-14. vi. Examined 3-6 days after moulting, 8 adults 
appeared pale and 3 slightly pigmented. 
( h ) Gray box, contained 32 eggs laid 28-29. vi. 18. Hatching began 3. vi., 
and 7 adults emerged 14-17. vi. Examined 5-8 days after moulting, the 
insects (as checked by the colour scale) appeared as a whole slightly darker 
than those in lot (e). 
Possibly owing to lack of ventilation, the number of lice raised to maturity 
in boxes B ( f-h) was smaller than in boxes A (c-e), i.e. 25 from 87 eggs as 
compared to 54 from 88 eggs. Otherwise there was no material difference in 
the rate of development. In Expts. III-VI that follow, the boxes were stood 
in the thermostat with their fenestra uppermost. 
Experiment III (second generation on black and white). 
The eggs laid (a) in the black box by dark adults, and (b) in the white box 
by pale adults in Expt. I, were maintained in said boxes. In the black box, 
hatching began 15. vi. and adults began to emerge 26. vi. In the white box, 
the corresponding dates were 16. vi. and 28. vi. The hatching period was one 
day longer in the white box and the developmental period (1st larva to adult) 
was two days longer than in the black box. The adults in the black box were 
very dark, those in the white box pale, the moulted skins of the immature 
stages being correspondingly dark and pale. These lice, representing the 
second generation raised on black and on white respectively, were neither 
darker nor paler than specimens of the first generation similarly raised. 
Experiment IV (transferring dark lice to white and vice versa). 
The dark adults of Expt. I were transferred to a white box and the pale 
adults to a black box on 11. vi. 18, where they laid eggs that began to hatch 
19. vi. The adults began to emerge 31. vi. The progeny of the pale lice raised 
on black were dark throughout and vice, versa. 
Experiment V (black and white). 
Adults raised on black cloth and consequently dark, to the number of 
2 dd and 3 $$, were placed on 2. vii. 18 in each of six boxes arranged as 
described below. The adults laid eggs which began to hatch 10. vii., and the 
adult offspring began to emerge 21. vii. The offspring were examined on 
23. vii. and all the moults of the six lots collected and separately mounted on 
slides. 
