PKEFACE. IX 



one thing, the dry land another. This land 

 will grow swedes and that corn, this rye-grasSj 

 and the other some other crop. He knows 

 what species of food, and what variety of it, 

 will fatten his stock the quickest. He knows 

 what roots and cereals are the most productive 

 and pay best, and in what order they should be 

 planted. He knows what breeds of stock suit 

 his farm, and where to put them, and when it 

 is most profitable to him to get rid of them^ 

 As a breeder and feeder, he knows how to cross- 

 breed and feed his stock, so as even to change 

 the very frames and carcasses of his cattle into 

 the shape most favourable to his interests ; and 

 how has he arrived at all this, but by study 

 and experiment ? 



Contrast our knowledge of water-culture with 

 that of agriculture, and the result is simply 

 degrading. We should know what kind of 

 food suits our various fish best, and what con- 

 ditions best produce that food, and how those 

 conditions are best to be cultivated, so that such 

 food may he self -producing. Hence it will be seen 

 that the habits of all the insects and plants found 

 in water, and their correlative agreements and 



