NESTS OF SPIDERS. 53 



cate eggs which lie warmly covered up at the bottom. 

 Taking one of them up on the point of the knife, and 

 laying it on the microscope-field, we shall be able to 

 see something of the anatomy of an insect's egg. 



First, we may notice what seems 

 to be the shell; that is, the outer 

 covering of the egg. This is very dif- 

 ferent to the hard, calcareous egg- 

 shell of birds. It is stated not to con- 

 tain any lime in its composition as 

 the shells of birds do ; for when the 

 eggs of insects are put into very 

 weak sulphuric acid and water, which 

 would act on the lime if it were pre- 

 sent in their composition, they are not 

 affected by it. Although, therefore 

 some eggs of insects are very hard: 

 so hard indeed as to resist severe pres- 

 sure with the nail, they do not owe 

 their hardness, as do the eggs of 

 birds, to any lime in their chemical 

 composition. The outer coat or shell is Nests ofspiders , 

 apparently simply membraneous, frequently vary- 

 ing greatly in thickness, being sometimes as dense 

 and horny as we have mentioned, and at others, so 

 delicate as to burst with the gentlest toiich. 



