Séance du 16 Avril 1924 
131 
than 397 young, and out of the 35 females which 
made egg-cases only 11 had more than 100 while 8 
had no young at all. 
It is therefore clear that at the best not more 
than half of the potential young are produced. 
7. Hatching. 
In the case of fertilized egg-cases, emergence 
usually takes place throughout at the same time, on 
the other hand it very seldom does so in the case of 
unfertilized egg-cases. Young may emerge on several 
days, sometimes a few each day and sometimes one 
or even two days elapse between successive emer¬ 
gences. The longest period we have on record' for 
fertilized egg-cases is three days, except for one which 
was broken in two while removing it from the box 
in which it was laid. This removal is necessary, not 
only for purposes of labelling and separate observa¬ 
tion, but to prevent the young being eaten by their 
mother when they begin to emerge. In this case the 
first, and largest, emergence took place on the first 
of October and the last on the sixth, on which day 
only one emerged; there were no emergences on the 
fifth and only two on each of the preceding days. In 
the case of unfertilized egg-cases, it usually takes 
two or three days, frequently four and sometimes 
five days for the emergence to be completed. 
For fertilized egg-cases, there is usually one 
main period of emergence, lasting only a short time, 
the remaining young being very few and coming 
