102 MR. A. MUBEAY ON THE EAELT STAGES OF 



1. A grub in the egg. (The first egg of the Blatta.) 



2. A cocoon in the egg, containing the unwiuged, imperfectly 

 developed insect. (The Leaf-insect.) 



3. An unwinged, imperfectly developed insect in the egg, free 

 from the cocoon, and ready to emerge. (The second egg of the 

 Blatta.) 



I have now to acknowledge and to show that, as regards the 

 first, I was in error ; the creature whose back looks so like one in 

 the egg is not a grub. As regards the second, I have already 

 shown that this was merely the yelk hardened into a cocoon-like 

 shape. And as regards the third, it is quite true, but, without the 

 first and second, proves nothing of what either Professor Owen or 

 myself thought to exist. 



Since the publication of these papers (now six years ago), I have 

 always wished for the opportunity of investigating the matter fur- 

 ther, but, until the present year, never enjoyed it. I have already 

 told what I have found in this year's arrival of Leaf-insect eggs. 

 I shall now explain what I have learned from the Blatta. In 

 Scotland (my former residence) Cockroaches are only exceptionally 

 abundant, and I never had the good luck to have any in my house. 

 Since my removal to London, 1 cannot complain : I have the hap- 

 piness to live in a house that is overrun with them, and I have 

 friends through whom I have sec\xred specimens from ships in the 

 docks. JSTowithstanding this emharras de richesses, I have found 

 surprisingly few eggs, and most of those which I did get were 

 already opened or advanced to the stage of No. 3. On having 

 recourse to the gravid female, however, I have obtained, by the 

 Caesarean operation, two or three half-developed eggs, a careful 

 examination of which compels me to own that the interpretation 

 I put on the African egg with the grubs is not borne out by facts. 



The half-developed egg is comparatively much narrower, although 

 not greatly shorter, than the full-grown egg. On opening one of 

 these soft, pale, and flaccid egg-cases, I found what, to all appear- 

 ance, was a row of glistening white grubs. Had I stopped there 

 (and that was all the length the dried African specimen allowed 

 me to go), I could have sworn it was a row of grubs ; but, placed 

 under the microscope, the scene changed. The first thing that 

 attracted my attention was a pair of flag-like flaps at one end. 

 This I soon found to be the anal projections at the tail of the per- 

 fect insect. The other part seemed rounded, but on a little pres- 

 sure being given to the glass, out gushed from under the thorax, 

 where it had been closely packed up, a whole quantity of sausage- 

 like matter. Can these be the intestines ? thought L It was 



