52 PHYSIOLOGY OF THE EGGS 



the vital principle in the eggs of insects ; and it has 

 been often noticed that, after a severe winter, insects 

 were more numerous in the succeeding spring and 

 summer. 



We now proceed to give an account of the sub- 

 stance of the eggs of Lepidopterous Insects. These, 

 like those of birds, consist, first, of a coat, or shell, 

 which is strong, flexible, and much of the consistence 

 of honey. It will not easily yield to the knife. It 

 contains little calcareous matter, if any at all, and 

 consequently resists the action of the muriatic and 

 other acids. 



With the composition of the fluid, which is 

 contained in these minute shells, we are not at all 

 acquainted, and can only suppose that it is analogous 

 to the white and yolk of birds' eggs. When the 

 egg has arrived nearly to the time of hatching, the 

 embryo may be distinctly seen by the use of a strong 

 microscope, coiled up in an annular form, as in the 

 following figure of the egg of a Priest-hawk Moth, 

 (Sphinx ligustri.^) 



Some of the eggs of this order of insects are 

 covered with hair, or a downy substance, as may 

 be instanced in those of the Figure-of-eight Moth 

 (Bombyx cceruleocephala.'} 



