136 
Biology of Pediculus humanus 
The Author’s Observations. 
The following experiments were designed to control those of Bacot 
above described. The lice were fed twice daily and kept at 32° C. 
Stated briefly, Bacot’s conclusions were (a) that corporis seldom if 
ever lays eggs on hair in the presence of cloth; ( b ) that capitis almost 
invariably lays eggs on hair in preference to cloth; (c) that corporis is 
less expert than capitis in the manner of ovipositing on hair. These 
statements will be considered in the same order as follows: 
(a) Does corporis lay on doth in preference to hair ? Three experi¬ 
ments were carried out to answer this question: 
Expt. 1. A thin brush of human hair was constructed by gumming 
a row of hairs between strips of paper fixed upon a piece of glass measur¬ 
ing 3 x | an inch, the hairs projecting half an inch. A piece of woollen- 
cloth measuring 3 x \ an inch was laid upon the paper on the glass, con¬ 
sequently the surfaces of cloth and hair, viewed from one side, possessed 
the same superficial area (see Fig. 6 D, p. 123). Two lots of corporis 
99 were placed respectively on two of these apparatus, and after 48 
hours they had laid (A) 18 eggs on cloth and 12 on hair; (B) 10 eggs 
on cloth and 11 on hair. 
Expt. 2. A long knotted thread of human hair was wound around 
three fingers and knotted in the centre (Fig. 6 B). The skein of hair 
was laid on the floor of a cell (Fig. 6 A) and a piece of felt the size of a 
slide laid upon it. Several corporis 99 were placed in the cell and after 
24 hours they had laid 9 eggs on felt and 18 on hair. 
Expt. 3. A hair-frame (Fig. 6 C) was placed in a cell with a piece 
of cloth resting upon it. Several corporis $9 after 5 days had laid 9 
eggs on the cloth and 86 on hairs. 
Taking the total number of eggs laid in the three experiments, 
there were 46 deposited on cloth or felt and 127 on hair. The relative 
number deposited on cloth and hair differed considerably in each 
experiment, nevertheless the results do not confirm Bacot’s statement 
that corporis seldom lays eggs on hair in the presence of cloth; in fact 
they preferred hair to cloth. 
(b) Does capitis lay on hair in preference to cloth ? Three parallel 
experiments to the foregoing were performed: 
Expt. 1'. The 99, after 48 hours, had laid 33 eggs on hair and 4 
on cloth. 
Expt. 2'. The 99, after 24 hours, had laid 10 eggs on hair and 0 
on felt. 
