Royal Physical Society. 39 



the insect has passed out of the capsule and out of the egg, 

 and where both the outer chorion and the skin of the capsule 

 may be seen one within the other. These circumstances im- 

 ply that the capsule is not a yolk ; because if it had been a 

 yolk surrounded by albumen within the chorion which had 

 dried up, it would not have preserved a determinate form, and 

 it would not have had a membrane round the capsule (quasi- 

 yolk). A yolk has not a membrane round it like the chorion 

 round the albumen ; and the yolk or interior of the egg in 

 drying up does not assume a determinate form. Farther, in 

 the eggs of insects which emerge from the egg in the larva 

 state, there is only found one membrane (the chorion), the same 

 as in a hen's egg. I refer to a specimen of the egg of one of 

 the largest coleopterous insects known (the longicorn, Titanus 

 giganteus), where it will be seen that there is only a single 

 membrane or chorion surrounding a dried amorphous mass. 

 This capsule, then, not being the yolk or original contents of 

 the egg, we are driven to look for some other explanation 

 of its form and appearance ; and these considerations tend- 

 ing to confirm the view suggested by the analogies of the sub- 

 ject, I do not hesitate to submit as an explanation, that the 

 capsule in question is the chrysalis of the leaf-insect, and that 

 the same physiological arrangement will be found in all or- 

 thopterous and hemipterous insects. 



It cannot be urged as an argument against this view, that 

 what I consider the perfect insect changes its skin a certain 

 number of times. The larva changes its skin ; and nobody 

 thinks that on that account it has ceased to be a larva. The 

 perfect crab changes its skin; and we still look upon it as per- 

 fect as before. That specialty, therefore, has no relevance. 

 A more embarrassing fact is, that after emerging from the 

 egg, changes take place on the form of the insect, and impor- 

 tant organs are altered or appear. As I shall presently men- 

 tion, an important alteration takes place in the antennse ; and 

 large wings, which are wanting on the first appearance of 

 the insect out of the egg, finally emerge. But it is to be ob- 

 served that all these changes take place in the way of gradual 

 growth, something like the appearance of teeth in the mam- 

 mal. The wings begin to bud out of the back after the first 



