Royal Physical Society. 42 L 



the natives, and these cases were covered with the paint. No 

 insect could have emerged without breaking through the case 

 and the paint, which were both uninjured. I presume, at a 

 certain stage on their passage homewards, the cold had killed 

 them, and I found the mummied remains as I have described. 

 In my former paper on this subject, I think I distinctly 

 showed the existence of a cocoon found in the egg of the leaf 

 insect ; and combining these particulars, we have the follow- 

 ing chain of facts : — 



1. The grub in the egg. 



2. A cocoon in the egg, containing the unwinged, imper- 

 fectly-developed insect. 



3. The unwinged, imperfectly-developed insect in the egg, 

 free from the cocoon, and ready to emerge. 



These facts appear to form a. pretty secure basis for holding 

 that the course of metamorphosis, in this class of insects, does 

 not differ from that in the other classes, except that the larval 

 stage and pupa stage are passed in the egg, instead of in the 

 open air, — and also probably with this qualification, that the 

 usual changes of skin, which in other insects take place in 

 the larval stage, do not here take place at that period ; but, as 

 it would appear, for some reason which we have not yet dis- 

 covered, that it is essential to the economy of insects that 

 they should cast their skins a certain number of times, the 

 orthopterous and hemipterous insects perform this necessary 

 step after passing from the pupa state, instead of before en- 

 tering it. 



There is another point, bearing upon this question, which I did 

 not sufficiently consider in my former paper. In it I stated that 

 in the leaf insect the sexual organs did not appear to be fully 

 developed until the last change ; and I endeavoured to account 

 for this as being analogous to similar changes in other animals 

 on reaching the age of puberty. But I now see reason to mo- 

 dify this expression of my views, or at least to limit this non- 

 development to the younger stages of these individuals, as, for 

 instance, before they have changed their skin at all. In such 

 very young individuals the sexual organs may not be, and 

 probably are not, fully developed ; but I am now satisfied that 



