8 



goes to make bulk and weight. The fact that this class 

 of animals will live a long time without eating anything 

 is familiar to all. There is but little waste of their sys- 

 tem in any way. We frequently see birds and fishes 

 kept in the same rooms, while the first are restless and 

 need constant care and feeding, and frequent cleansing of 

 their cages, "the latter are almost motionless, unless dis- 

 turbed ; and as the water in which they are kept is usually 

 clear and fresh, it has in it but little food. 



It may be true that a pound of fish does not contain as 

 much nourishment as a pound of beef, but the difference 

 is by no means as great as the difference in the cost of 

 production. For some purposes of health it is much 

 more valuable than a like weight of other food. Less 

 care and labor are needed to raise fish than to raise other 

 animals, or even to raise vegetables. We must give close 

 attention to our flocks and herds throughout the year, and 

 we must toil through a long season in our fields to make 

 vegetables grow. Lakes and rivers are well said to be 

 like fields prepared for seed. Fish only need our help in 

 one way. At breeding times their eggs are mostly des- 

 troyed by numerous enemies, and but few are hatched. 

 By artificial means at a trifling cost nearly all the eggs 

 can be saved, and vast numbers of young produced. 



While on this analogy, it may be suggested that rota- 

 tion of crops may be as advantageously introduced in 

 piscicultute as in agriculture. In a portion of France, 

 where the land is low and can be overflowed at pleasure, 

 by a system of dyking, crops of grain and eels are alter- 

 nated, the latter being the most profitable, but this is 

 only the germ of the true principle. When one sort 

 of root or grain or vegetable is repeated on the same 

 land, it is found that the soil is exhausted of its food, 

 while its enemies are augmented in number. Identically 



