16 INSECT TUANSFORMATIONS. 



but the down upon the et^gs of insects does not 

 conduce to this end. Whether insect egi^s be naked 

 or clothed with down, they are invariably, as far as 

 their history has been investigated, deposited close to 

 or upon substances capable of affording food to the 

 young when hatched. In making experiments upon 

 the specific gravity of eggs, it should be remembered 

 that no infertile or unimpregnated egg will sink; 

 for having some hundreds of these laid by dif- 

 ferent species of insects reared in our cabinet, 

 we found, upon trial, that they uniformly floated, 

 while those which we knew to be impregnated 

 as uniformly sunk. A female, for example, of the 

 rose-leaf roller {Lozoticnia Rosana, Stephens) 

 was reared by us, in solitude, under an inverted 

 wine-glass, uj)on the side of which she glued a 

 patch of eggs, of course, unimpregnated ; these, upon 

 trial, all floated in water. But eggs of the same 

 species taken from the outside of a pane of glass 

 close to a rose-tree, all sunk in water ; and it is to be 

 fairly presumed, as the parent of the latter was in a 

 state of freedom, that these were impregnated. We 

 found the same distinction, indeed, to hold in the 

 eggs of the drinker moth, the gipsy moth, and 

 numerous other insects*. 



Dr. Good's account of " honey dew," which he 

 describes as " a peculiar haze or mist loaded with a 

 poisonous miasm," that stimulates " the leaves of the 

 hop to the morbid secretion of a saccharine and viscid 

 juice" — appears to us unsupported by facts. Lin- 

 naeus t, on the contrary, who was not wedded to the 

 meteorological theory of a miasmatous haze, ascribes 

 the honey-dew on the hop leaves to the caterpillar of 

 the ghost moth {Hepialus hiimuU) attacking the 

 roots. Dr. Withering, favouring this account, re- 

 commends covering the roots with stones as a preveu- 



* J. R. t Quoted by Keith, Phys, Bot., ii. 143. 



