66 



The Naturalibt. 



insects like the genus Leucania, Fieris, &c. But, on the other hand, 

 Mr. Cole is reported to have bred a series of Ennomos angularia, 

 which differed slightly according as the larvag were fed upon oak, 

 thorn, lime, or lilac. It might be that in some cases a variety is 

 caused by some disease or want of energy ; and it is worthy of note 

 that many varieties either never leave the pupa case, or are crippled. 

 We frequently find plants single shoots of which are either variegated 

 or completely white, and the cultivator has often taken advantage of 

 this, and propagated the variation. I have particularly noticed in the 

 common dock that some portion of the leaves of some particular 

 plant has been variegated with white or yellow, frequently divided in 

 each leaf by the midrib, one half being green and the other half 

 yellow. The common cultivated geranium will often send out a 

 branch upon which all the leaves are white ; and I know a gardener 

 who has frequently cut these branches off and tried to grow them 

 separately, but hitherto they have always withered and died, whereas 

 if he had cut off an ordinary green branch, probably it would have 

 grown without any hesitation — seeming to show that the white 

 branch was diseased or had a want of energy. This want of energy 

 seems to be present in those insects which are unable to burst from 

 the pupa case, or, having burst therefrom, are unable to expand their 

 wings to maturity. The two cases seem to be analogous, only with 

 this difference — that when plants are diseased from what I call a want 

 of energy, they generally assume a pale form, whereas many of the 

 crippled varieties of insects are darker than the normal type. 



In cases where the insects have bright red — as in the tigers and 

 burnets — the red has a tendency to become yellow ; and Mr. Bond 

 pointed out to me that the yellows (as in Flantaginis^ have a 

 tendency to become red. But this is by no means universal, and in 

 the few cases we know of, might it not be that the insects were 

 originally red, and the cases of red variation we see now are cases of 

 reversion to the original stock ? I think there are more cases of 

 reversion than we are at present led to suppose. Halia wavaria is a 

 tolerably constant insect, but now and then we see one of a uniform 

 dark slaty brown. Cahera pusaria, another constant species, occa- 

 sionally comes out a dark leaden colour, and if these be simply 

 " sports," it seems strange that they should be all exactly the same. 

 A. cardamines I have seen with the ground of all the wings yellow, 

 which seems like a reversion to some of the yellow species of Antlio- 

 charis found on the Continent. A specimen of C. caja in Mr. Sydney 

 Webb's collection, in the appearance of the under wings seems to 



