140 Bulletin de la Société Royale Entomologique d'Egypte 
11. The Rate of Development. 
The rate of development is affected not only by 
changes in temperature, but also by accidents which 
happen to the individual, especially at the time of 
moulting. Our boxes were square glass-topped boxes 
of the type usually supplied by dealers and the paper 
inside was rather too smooth, so that most of the ac¬ 
cidents which occurred were due to the falling of the 
insect while moulting. These were not always fatal 
and injured parts were frequently regenerated com¬ 
pletely, but the development was in many cases 
lengthened. In addition there are individual variations 
which are sometimes very marked, without any ap¬ 
parent cause to explain them. In particular, the num¬ 
ber of moults varies; there are usually seven, fre¬ 
quently eight and sometimes only six. 
The number of adults obtained from unfertilized 
egg-cases is too small to allow us to study the effects 
of these various factors or to compare the results with 
those obtained from fertilized egg-cases. A discussion 
of these results would therefore be out of place here. 
We shall merely state that there is no evidence 
kJ 
that the virginity of the mother affects the number 
of moults of her descendants and that, if the rate of 
development is affected, it is lengthened slightly. 
12. The longevity of the Females of the Second Generation. 
The winter months may be passed in any stage, 
development being practically arrested in the nymphs 
