FOOD OF FISH AND ITS PEODUCTION. 103 



production of certain water insects, from Timbuctoo 

 or elsewhere. There must also be a vast number of 

 water insects, which would prove valuable to our 

 fisheries if introduced, provided we knew all about 

 them. 



I think I have said enough to show that there is 

 here a very wide field for discovery. Here is, as 1 have 

 said, a new world a new science to be learnt. The 

 modern taste for aquariums and vivariums has given 

 us some small insight into how to cultivate those 

 plants which we already possess, which are the best 

 calculated to look well in the tanks, but we do not 

 study even these to discover the natural duties and 

 uses for which Providence designed them. We do 

 not in a like manner work out the properties of the 

 insects that inhabit them ; and what could be more 

 easy, or would be more interesting, to the entomo- 

 logist, than to watch the changes and the habits of 

 the various insects that people the waters to see 

 the most delicate, beautiful, and harmless little flies 

 in creation spring from curious and ungainly grubs, 

 or fierce predaceous larvae, changed in form as in 

 nature, to a degree altogether unaccountable ! What 

 wonderful and interesting processes would not reveal 

 themselves to the curious observer ! How encouraged 

 he would be to note each new fact, and record every 



