Gr. H. F. Nuttall 
123 
to which the female clings. Already in the ovary, the egg shows 
asymmetry; this is clearly seen in eggs attached to hairs where 
they can be viewed in profile (Fig. 4 B). Thus viewed, the ventral 
contour appears relatively straight, the dorsal curved and slightly 
shortened to where it joins the operculum; the egg is broadest a short 
distance behind the operculum, whence it gradually tapers basally. 
The orientation of the egg is such that when the young larva emerges, 
it is able to grasp the hair or fabric directly it issues, the operculum 
Fig. 6. (A) Glass cell used for confining lice under experiment. (B) Skein of human 
hair as used in experiments on oviposition. (C) A hair-frame, consisting of copper 
wire or glass with hair wound about it and interlaced where the hairs cross. (D) Hair 
brush with strip of cloth of corresponding superficial area laid upon its base. (All 
figs, frds natural size.) 
mostly springing open on the ventral side; the mechanism of hatching 
will, however, receive consideration elsewhere (see p. 148). 
The cement that serves for the attachment of the eggs is secreted 
by large glands opening laterally into the uterus; it flows about the 
hair and base of the egg and is drawn between them by capillarity; 
its flow ceases before the broader opercular portion of the egg has issued, 
and this explains why it is always the posterior part of the egg which 
is cemented to the substratum; moreover, if the cement continued to 
flow out after the egg it would occlude the pores of the operculum. 
