The Glow- Worm and Other Beetles 



experiment I have discovered grains of uric 

 acid in the adipose tissue of the larvae of all 

 the Hunting Wasps of our parts, as well as 

 in the Bees at the moment of the nymphosis. 

 I have observed them in many other insects, 

 either in the larval or in the perfect state ; but 

 in this respect there is none to equal the grub 

 of the game-hunting Wasp, which is all 

 speckled with white. I think I see the rea- 

 son. 



Let us consider two larvae which eat live 

 prey: that of the Sphex and that of the Hy- 

 drophilus. 1 Uric acid, the inevitable pro- 

 duct of the vital transformations, or at all 

 events one of its analogues, must be formed 

 in both. But the Hydrophilus' larva shows 

 no accumulation of it in its adipose layer, 

 whereas the Sphex' is full of it. 



In the latter the duct through which the 

 solid excretions pass is not yet in* working or- 

 der; the digestive apparatus, tied at the lower 

 end, is not discharging an atom. The uri- 

 nary products, being unable, for want of an 

 open outlet, to flow away as formed, accumu- 

 late in the adipose tissue, which thus 

 serves as a common store-house for the 

 residues of the present and the plastic ma- 

 terial of the future organic processes. 



1 The Great Water-beetle. Translator's Note. 

 278 



