STATES OF INSECTS. (Lgg.) 103 
pilar till the April following’. We know no more of 
the cause of this difference than of that which takes 
place in the period of exclusion of the eggs of the dif- 
ferent species of birds. 
Some eggs change considerably both their form and 
consistence previously to being hatched. M. P. Huber 
found that those of different species of ants when newly 
laid are cylindrical, opaque, and of a milky white; but. 
Just before hatching their extremities are arched, and they 
become transparent with only a single opaque whitish 
point, cloud, or zone, in their interior’. An analogous 
change takes place in the eggs of many spiders, which 
just before hatching exhibit a change of form corre- 
sponding with that which the included spider receives 
when its parts begin to be developed, the thin and flexible 
skin of the egg moulding itself to the body it incloses*. 
In proportion as the germe included in the egg is ex- 
panded, it becomes visible through the shell when trans- 
parent: this-is particularly the case with spiders, in 
which, as was before observed, every part is very di- 
stinctly seen. At length, when all the parts are consoli- 
dated so as to be capable of motion, which in spiders 
takes place in four or five days after they begin to be 
visible in the egg, the animal breaks the pellicle by the 
swelling of its body and the movement of its legs, and 
then quits it, and disengages all its parts one after the 
other’. In general, at least where the shell is harder 
than that of spiders, insects make their way out by gnaw- 
ing an opening with their mandibles in the part nearest 
their head, which, when the shell is very strong (as in 
2 Rimrod Naturf. xvi, 131. b Fourmis, 69. 
© De Geer vii. 195. 4 Jbid. 196. 
