[105] POND CULTURE. 571 



rapidly, should be fed on articles contaiuiug- a great deal of nitrogen. 

 After giving the above data, we shall now endeavor, proceeding by 

 analogy, to ascertain, on the basis of the hiws which regulate the feed- 

 ing of various domestic animals, that proportion of nutritive substances 

 which is most favorable to the development of carp, and the (piantity 

 in which the food should be administered. 



Tlie substances composing the various articles of food of the higher 

 classes of animals are divided into those which contain nitrogen and 

 those which are free from nitrogen. To the former belong the proteine 

 or albuminous snbstances, to the latter the hydrates of carbon and fat. 

 Vegetable food contains comparatively much less nitrogen than animal 

 food. The most profitable method of feeding domestic animals is that 

 which provides the qnantity of nntritive matter which is best suiteil to 

 the pnrpose these animals are to serve, and provides it in the proper 

 proportion, i. e., the right proportion between the digestible albuminous 

 substances and the digestible hydrates of carbon, including fat. The 

 substances containing nitrogen — in other words, the albuminous sub- 

 stances in the various changes which they undergo in the animal body — 

 mainly serve to form fiesh and fat, while those substances which con- 

 tain but little nitrogen principally serve the i^urposes of respiration. 



By comparing the different methods of feeding domestic animals, 

 chiefly cattle, whose food belongs exclusively to the vegetable kingdom, 

 and the different kinds of grass of good pasture-lands, in which the 

 proportion of nutritive matter — i. e., the proportion between the sub- 

 stances containing nitrogen and those which do not contain it, is as 1 to 

 from 5 to G — it has been ascertained that the most profitable proportion 

 of luitritive substances is about 1 to 4 or 1 to 7. Professor Wolff says : 

 " If the food contains less albumen than would correspond to the pro- 

 portion 1 to from 6 to 7, a considerable portion is not properly digested 

 and absorbed, and a i^art of the ntttritive sul)stances which do not con- 

 tain nitrogen is x>assed with the excrements, without having been of 

 any use to the body. If the proportion exceeds that of 1 to from G to 

 7, there is not sufficient albuminous matter to attain the desired pro- 

 duction quickly and safely, it progresses slowly and without energy, 

 so that in the end the profits are very small, even if the food has been 

 very cheap. A proportion like that of 1 to 4 is never needed in feeding 

 domestic animals, as it would tend to further the disintegration of mat- 

 ter in the body and cause losses in the end. But if the absolute 

 quantities of the nutritive stibstances containing nitrogen and of those 

 which are free from nitrogen are sufficiently large and do not exceed 

 the proportion given above as the most suitable, all reasonable require- 

 ments have been met. l!>ro losses need then be feared by a relaxation 

 of the digestive organs or too great a disintegration of matter ; nor 

 will there ever be a lack of material to favor quick and ample produc- 

 tion. The most suitable proportion for purposes of production will, 

 therefore, be somewhere between 1 to 4 and 1 to 7 ; although it may be 



