STATES OF INSECTS. 103 



this difference than of that which takes place in the 

 period of exclusion of the eggs of the different 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 a . 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 b . 



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 c . In general, at least where the shell is harder 

 than that of spiders, insects make their way out by 

 gnawing an opening with their mandibles in the part 

 nearest their head, which, when the shell is very strong 

 (as in Lasiocampa Neustria, &c), it is often several 



a Fourmis. 69. b De Geer vii. 195. c Ibid. 196. 



