H INSECT TRANSFORMATIONS. 



patches of which may be found on many sorts of 

 leaves during' the summer months. 



The immediate origin of colour in the eg'o's of in- 

 sects is ill some cases the inclosed yolk shining 

 through the transparent shell ; but in others, the 

 shell is not uniformly transparent, but ringed, banded, 

 or dotted with opacities of various colours. In the 

 eggs of the driid^er moth {Odoncstis potatoria), for 

 example, there are two circular rings of a green 

 colour, from the green yolk appearing through the 

 shell ; while the rest of the shell is white and opaque, 

 as we have proved by dissection *. Certain ruddy 

 spots on the white eggs of the small rhinoceros 

 beetle (Oryctes 7iasicor}iif}, Illiger) were discovered 

 by Suammerdam to be the red mandibles and spi- 

 racles of the unhatched grub seen through the shell; 

 and the white ground, we infer, was similarly caused 

 by the body of the grubt. This, however, cannot 

 be the origin of the bright red spots on the beautiful 

 yellow egg of the brimstone moth {Rwnia crat^gata, 

 Duponchel), which may, perhaps, have a similar 

 origin to those of birds. 



With respect to the eggs of birds, it has been re- 

 marked by Mr. KnappJ, that in those "of one hue, 

 the colouring matter resides in the calcareous part ; 

 but where there are markings, these are rather ex- 

 traneous to it than mixed with it The elegant blue 

 that distinguishes the eggs of the fire-tail {Sylvia 

 phoeniciirus, Lath.), and of the hedge-sparrow, 

 tliough corroded away, is not destroyed by muriatic 

 acid. The blue calcareous coating of the thrush's 

 vgg is consumed ; but the dark spots, like the 

 markings on the eggs of the yellow-hammer, house- 

 sparrow, magpie, &c., still preserve their stations on 



» J. R. 



f Swammerdam, Book of Nature, i. 13. 

 X JouriKil of a Naturalist, p. 230 



