ECONOMY OF NUTRITIVE MATTER. Gl 



bones.* These, again, are the favourite repast 

 of the Hyaena, whose powerful jaws are pecu- 

 liarly formed for grinding them into powder, 

 and whose stomach can extract from them an 

 abundant portion of nutriment. No less speedy 

 is the work of demolition among the inha- 

 bitants of the waters, where innumerable fishes, 

 Crustacea, annelida, and mollusca are on the 

 watch to devour all dead animal matter which 

 may come within their reach. The consumption 

 of decayed vegetables is not quite so speedily 

 accomplished ; yet these also afford an ample 

 store of nourishment to hosts of minuter beings, 

 less conspicuous, perhaps, but performing a no 

 less important part in the economy of the creation. 

 It may be observed that most of the insects which 

 feed on decomposing materials, whether animal 

 or vegetable, consume a much larger quantity 

 than they appear to require for the purposes of 

 nutrition. We may hence infer that in their 

 formation other ends were contemplated, besides 



* So strongly was Linnaeus impressed with the immensity of 

 the scale on which these works of demolition by insects are car- 

 ried on in nature, that he used to maintain that the carcass of a 

 dead horse would not be devoured with the same celerity by a 

 lion, as it would be by three flesh flies (Musca vomitoria) and 

 their immediate progeny ; for it is known that one female fly will 

 give birth to at least 20,000 young larvee, each of which will, in 

 the course of a day, devour so much food, and grow so rapidly, 

 as to acquire an increase of two hundred times its weight ; and 

 a few days are sufficient for the production of a third generation. 



