122 
Biology of Pediculus humanus 
single hair, all of them pointing in one direction. Fig. 5 shows them 
similarly placed on pubic hair. This latter appearance is commonly 
seen on the heads of persons heavily infested with head-lice and it 
may be observed under experimental conditions both with capitis and 
corporis. From the fact that the latter often oviposit deep down in 
the interstices of felt or in seams of clothing (in soldier language 
they “dig themselves in” according to Peacock), it is evident that 
they must also walk backward and then forward on fabrics when 
about to oviposit, in the same way that we have seen them do 
on hair. 
It is worthy of note that most of the eggs laid on hair in my experi¬ 
ments were orientated in one way. On the hair-brush (Fig. 6 D) 
used for experiments with corporis and capitis all the eggs (23 and 
Fig. 5. P. humanus ( capitis ) eggs on pubic hair shaved from a soldier; the base of the 
hair having been cut through very close to the base of one egg. The hair bears 
six unhatched eggs all pointing to the distal end of the hair with their opercula; 
some eggs show the eyespot of the developing larva. All the lice on the soldier 
were confined to the pubis (see p. 86). Drawn from hving specimens with the 
aid of a camera lucida. 
33 respectively) were laid with the operculum directed toward the 
free end of the hair exactly as on the human head. On hair-frames, 
in the eggs laid near the glass or copper frame, most of the opercula 
pointed away from the frame, thus in two experiments corporis laid 
(a) 52 eggs directed in this way and only 4 reversed, and ( b ) 44 directed 
in this way and 8 reversed. The females usually go to rest near the 
artificial base of the hair (corresponding to the scalp) and as they lay 
they walk away along the hair in the manner observed by me in life. 
When laid upon cloth, their orientation is almost always the same, 
the ventral surface of the egg being attached along its posterior half 
to the substratum; in this respect it is indifferent whether the egg is 
fixed to hair or cloth. The ventral surface of the egg corresponds 
to the ventral side of the female whence it issues and the egg appears 
to issue invariably with the ventral side directed toward the substratum 
