6 INTRODUCTION. 



Imagine a man in difficult circumstances endea- 

 vouring to gain a livelihood by rearing some new 

 variety of dog, cow, horse, ass, or pig. He would 

 have greater chance of success were he to extract 

 some new colouring matter from the insect world, 

 or discover a means of doubling the produce of the 

 bee or the silkworm, or a method by which sponges 

 and corals might be cultivated with as much ease as 

 a lettuce or a cauliflower. 



My endeavour in this volume is to treat of 

 inferior animals useful to man, from insects down- 

 wards to infusoria and sponges. I leave it to others 

 to write the useful novelties that may concern 

 Quadrupeds, Birds, Reptiles, and Fishes. My obser- 

 vations treat of Invertebrata only. 



Our readers have doubtless heard of a new species 

 of culture which has lately taken a very extensive 

 development. It is called Pisciculture, or the breed- 

 ing of fish, in which many eminent naturalists have 

 met with astonishing success.* Their secret was, 

 however, known long ago to the Chinese. When a 



* See papers on the subject by Coste, De Quatrefages, and others, 

 and for the artificial propagation of the salmon in Great Britain, 

 see report of a committee, consisting of Sir W. Jardine, Dr. 

 Fleming, and Mr. E. Ash worth, in "Report of British Association," 

 1856. These researches are facilitated as regards fish by the great 

 fecundity of the latter. Thus, the pike, for instance, produces about 

 300,000 eggs ; the carp, 200,000 ; and the mackerel, more than 

 half-a-million. But this fecundity is still more astonishing in the 

 inferior animals of which we treat here. 



