238 
Bionomics of Pediciiliis 
Table I gives the record of 21 of P. humanus which were segregated 
in the larval stage and on reaching maturity were placed in rotation 
with a single d- Of these 21 $9 18 were more or less effectively fertilized 
by the one d- It will be noted that the 9? invariably commenced 
oviposition irrespective of their having paired; probably egg develop¬ 
ment is entirely a question of nutrition and laying is completely automatic 
while feeding continues at a favourable temperature. In no case did 
eggs laid by virgin 9? hatch. 
As regards the three 9? which laid only infertile eggs—it is probable 
that the death of No. 5 was connected with pairing, as she laid but one 
egg after the introduction of the d, and she died with the whole body 
and limbs as far as claws tinged with red. I suspect that death resulted 
from rupture of the alimentary canal due to violence during the sexual 
act. Deaths showing a similar post-mortem appearance are by no 
means uncommon. In the course of the experiments it was remarked 
that death frequently followed, if it did not actually occur during, the 
act of pairing if the 99 were nearing their age limit. 
In the case of No. 8 it is doubtful if pairing ever took place; this 
9 proved a poor egg layer, but the evidence available from the other 
99 which laid prior to pairing precludes any suggestion that low egg 
production resulted from infertihty; it is possible, however, that both 
the failure to pair and small egg laying capacity were the outcome 
of a low vitahty. 
Probably the d was too feeble to pair with No. 21, as he died the 
following day. Table V shows that there was no question in regard to 
the vitality of this 9 as she laid fertile eggs after she had been placed 
with another d- 
It was obvious early in the course of the experiment that abihty 
of the 99 to lay fertilized eggs after the removal of the d did not continue 
for life (see Table IV). In order to test the period, the 99 were removed 
to fresh boxes at a progressively shortened interval of time. The eggs 
laid in the second box are indicated by printing the figures in heavy type. 
By this means a general indication of the duration of fertility was 
attained; in the cases where eggs hatched which had been laid in the 
second box, showing definitely that fertility was still retained, the term 
“ at least” indicates that the number of days might have been more. In 
several cases the number of days has been calculated by counting the 
number of eggs laid in sequence up to the number which hatched and 
reckoning the number of days from the removal of the d up to the date of 
the last laid egg included in the total. In both cases it is probable, that 
