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retains its attachment to the cell wall by its hinder segments remaining in a 

 portion of the egg-shell, which is firmly attached to the cell-wall ; and a con- 

 siderable portion of the egg-shell may often be seen closely applied to the 

 ventral aspect of the last segments of the larva. The grub casts its skin four 

 times afterwards ; so that there are five stages or sizes of the larvte. In the 

 first the jaws are destitute of brown corneous tips ; afterwards the larva.- are 

 only distinguishable by their size. I have seen the cast skin between each 

 stage ; it is always accompanied by the linings of the trachea:, and a short 

 lining is drawn out of the mouth. Unlike most other larvrc, in moulting, the 

 head-covering is not cast as a complete corneous plate, but a mere skin is cast, 

 as from the rest of the body, the only corneous portions being the brown jaw 

 extremities, which are very distinct in each cast skin except the first, and serve 

 readily to distinguish to which moult the skin belongs. All these are very 

 slight, insignificant pellicles, except the last one and the one that is cast on 

 assuming the pupa state. The greatest proportion of its growth is made by 

 the larva after it has assumed its last skin. As the larva grows the wasps 

 build up the cell-wall around it. When the larva has finished feeding, it 

 voids a certain quantity of black matter, which forms a firm black cake at 

 the base of the cell; beneath it are the four cast skins of the larva. I have 

 examined this black deposit both before and after it is deposited, and I find in 

 it no portions of insects of any size, though there are many minute particles 

 that may be bits of chitine. It is, in fact, the effete material of the grub stored 

 up during all its existence. The grubs are fed by the wasps with only fluid 

 material : though the grubs work their jaws actively, they have very little (no ?) 

 power of biting or chewing. The larva; of the hornet make a great noise by 

 striking and scratching the walls of their cells with their expanded jaws. I 

 take this to be a call for food. The black material is evacuated just before the 

 grub begins to spin its silken covering ; and this is the only time at which its 

 alimentary canal is emptied. This is sufficiently proved by the store of black 

 matter in the grub's interior increasing in quantity with the growth of the grub, 

 and by the anal extremity of the grub being always enveloped in a cast skin ; 

 so that it is impossible to suppose that the wasps have removed anything. 

 Excepting, then, the amount of excretion in the form of vapour, it follows that 

 the wasp-grubs, from the egg to the perfect state, are actually fed upon an 

 amount of material of only their own bulk. 



"When the alimentary canal is emptied, the larva commences to spin its 

 silken covering ; and now it is far from being such an inert larva as it has pre- 

 viously been : it moves its head actively to and fro to spin a silken dome over 

 the mouth of its cell, and passes its head far down the cell-wall, to cover it 

 with silk. Further, now its last cast skin is buried beneath the black deposit, 

 it has no hold of the base of the cell by its anal segments ; and being kept 

 from falling out by the silken covering, it turns on itself so as to be quite 

 folded at its middle ; and I have frequently found such a larva completely re- 

 versed in the cell. Now there are two facts that prove, I think, that this 



