hettoeeii Wasps and Rhipiphori. 87 



bulk of many caterpillars. With the RJilpijyhorns there is 

 nothing of this. The assumption is that it attacks from with- 

 out. The wasp-larva or pupa has ceased to eat, or if not 

 already ceased, the attacks of its enemy will soon make it 

 cease ; and all that the little larva of the Blupqjhorus has to 

 feed upon and grow as large as the wasp upon is the one 

 mass of meat no larger than what it is to grow to. This 

 is the view which Mr. Stone and, following him, Mr. Smith 

 adopt. Mr. Stone's observation is that the Ehipij^horus-larva, 

 which he found attacking a wasp-larva in a sealed-up cell 

 (which, by the way, must only have been recently closed, or 

 it would have had within it not a wasp-larva, but a wasp- 

 pujDa) " was of minute size when discovered, and appeared to 

 have only recently fastened on its victim ; but so voracious 

 was its appetite, and so rapid its growth, that in the course of 

 the following forty-eight hours it attained its full size." Now 

 if by " minute size'''' we suppose a line or a line and a half in 

 length, it must have grown three or four times its own size in 

 forty-eight hours, which is so opposed to everything we know 

 of the laws of development and assimilation that I cannot 

 accept it. If we look at the little black deposit of digested 

 debris at the bottom of the wasps' cells, we find fragments 

 indicating the consumption of hundi-eds of insects not much 

 smaller than themselves : there is the same at the bottom of 

 the cells of the RMpifpliori -^ but I refrain from using that as 

 an argument, because Mr, Smith might plead that I cannot 

 prove that the black deposit in their cells was not the product 

 of former wasp-tenants who had been reared in the same cell. 

 Let it not be supposed for a moment that I at all doubt 

 that Mr. Stone thought he saw this ; but I think his observation 

 has been inaccurate ; and I try to account for it in this way : — 

 It is plain he could not have kept his eye constantly fixed on 

 this specimen for forty-eight hours ; we may assume that he 

 did not sit up two nights running to watch it. He saw it at- 

 tacking the wasp-larva and eating at it voraciously (the mean- 

 ing of that and of some other of his observations I shall dis- 

 cuss presently), and he left it so occupied. He returned to it, 

 how soon or how often he does not tell us ; but when he did 

 return, and found it so increased in bulk, I cannot but believe 

 that he mistook the cell, and, instead of looking into the one 

 he left, looked into another where was a mature B-Mpiphorus- 

 larva, which had had nothing to do with the meal on the 

 wasp. Any one who has ever tried the experiment of en- 

 deavouring to find a particular cell in a comb after removing 

 his eyes from it, for however brief a space, will know that 

 nothing could be easier than to make such a mistake. I can 



