THE EGG. IX 



conceals her eggs with a white, frothy substance that 

 hardens and protects them, from the weather. The female 

 Saw Fly makes, with her double saw, a longitudinal in- 

 cision in a leaf or a stem, and places in it her eggs, in a 

 single row from end to end, and then closes up the opening 

 with a green, frothy fluid, mixed with the small pieces of 

 leaf detached by her saws. Some moths surround their 

 eggs with hair, stripped from their own bodies. Many 

 make the leaves and other parts of plants serve as cover- 

 ing for their eggs. A great many insects, however, satisfy 

 themselves by covering the eggs with a water proof coat 

 of varnish and leaving them near the food the larvse 

 are to hve on when hatched. Some insects, as the Mos- 

 quitos and Gnats, deposit their eggs on the water, and let 

 them float as little rafts. A great many lay them on the 

 bodies of other animals, as on the hairs and feathers of 

 Vertebrates, or on the bodies of other insects, or even in- 

 deed in the eggs of other species. Others bury them in 

 the ground, either directly in the soil, or in the body of 

 some other little animal they have buried for the purpose. 



3. Substance. — The eggs of insects, as of birds, con- 

 sist firpt of an exterior shell or membrane, and second, an 

 internal vital fluid. This membrane is sometimes ex- 

 tremely delicate, and readily yields to evaporation if ex- 

 posed to the weather ; but among the Ijepidoptera^ and 

 several other tribes, this integument is considerably 

 stronger. 



The fluid within the egg contains the material out of 

 which the young larva is built ; and the study in the mi- 

 croscope of the several changes through which it passes is 

 an extremely interesting department of Emhryology, 



1. NuMP.Erv.. — The' number of eggs laid by an msect 



