130 Biology of Pediculus humanus 
On the 23rd day <j> A was found dead and crushed. Total eggs 203. 
Average 9* 6. 
On the 29th day $ B died. Total eggs 272. Average 9-7 per day. 
As the two females A and B were confined together, the eggs laid 
by each are apportioned equally in the protocol up to the death of <j> A ; 
the day of death, in the case of the latter, is excluded in computing the 
daily average. 
One A wa s lost on Day 7; the second $ was found dead on Day 28. 
As far as I am aware this is the only experiment of the kind that 
has hitherto been carried out. The daily inspection showed that the 
adults fed frequently, imbibing small quantities of blood at each meal; 
the insects never gorged to repletion as they do when fed but twice or 
thrice a day. It is probable that lice which feed at frequent intervals 
assimilate their food better than others which gorge after more or less 
prolonged starvation. This, combined with the uniform conditions of 
temperature and moisture, explain the high total and average number 
of eggs they laid per day. Only one of Bacot’s results shows that a 
female may lay up to 295 eggs, otherwise the highest totals recorded 
by Sikora and by Bacot are 197 and 180. Both of these authors 
allowed the adults but limited opportunities of feeding, and although 
Bacot’s method is ingenious it is imperfect. The highest average 
numbers of eggs laid per day hitherto recorded for limited periods are 
those of Leeuwenhoek (8) and Wilder (7) in lice confined in a stocking 
worn on man; the highest average for one female recorded for the whole 
oviposition period by Bacot (6-4) is distinctly lower, and does not 
compare favourably with the average of 9-7 per day obtained by me 
with $ B under natural conditions. I would add that an examination 
of the latter female soon after death revealed the presence of three small 
eggs in her ovaries. 
We may therefore conclude that under optimum natural conditions 
275-300 eggs represent the normal number of eggs which a female 
P. humanus is capable of laying, and that during the greater part of 
her oviposition period she lays 9-12 eggs a day, or an average of 9-7. 
The Number of Eggs Laid by Capitis in a Wristlet. 
Although the wristlet method (see p. 107) cannot be stated to afford 
natural conditions, it has yielded results in striking contrast to those 
previously obtained in repeated attempts to raise capitis experimentally. 
The number of eggs laid per day by a female, as will be seen from the 
