[117J POND CULTURE. 



583 



If we take food containing but little nitrogen, e. g., dry malt, we 

 would need 14,400 pounds, at 8 marks per 100 pounds=l,152 marks 

 [$2SS] ; of potatoes we would need 51,400 pounds, at 2 marks [50 cents] 

 per 100 pounds = 1,028 marks [$275J, and at 3 marks [75 cents] per 100 

 pounds=l,542 marks [8385.50]. A mere glance at these figures will 

 show that there will be an absolute loss. The expense of mixing with 

 a nitrogenous food some other food containing less nitrogen will be a 

 little higher than if a single article of food is employed whose propor- 

 tion of nutritive substances is very near the standard. If, for instance, 

 we use fish guano, it will be absolutely necessary to mix with it some 

 other food containing less nitrogen. We would get nearest to the 

 quantity (1,080 pounds albumen) and the standard proportion of nutri- 

 tive substances by mixing the following : 



2,360 pounds fish guano, at 10 marks [$2.50] per 100 pouucl8=236 marks [$59]. 

 2,000 pounds potatoes, at 2 marks [50 cents] per 100 pouuds=: 40 marks [$10J. 



276 marks [$69]. 



This would still yield a good profit, even if we count in some addi- 

 tional expense for cooking the potatoes, but it will never yield the same 

 profit as ground meat used by itself. The same results will, to some 

 extent, make themselves felt in cases where artificial food is employed 

 in addition to the natural food. 



It may, therefore, be laid down as a rule that, if artificial food is to 

 be used exclusively, ouly those articles of food should be employed 

 whose proportion of nutritive substances comes nearest to the standard, 

 or which contain a large quantity of nitrogen. The same rule applies 

 if artificial food is used only to supplement the natural food (as a devi- 

 ation fi-om this rule, though not of such serious consequences as in the 

 first case, will nevertheless prove injurious); and food containing little 

 nitrogen should only be used to restore the standard proportion of nu- 

 tritive substances, if the principal food is blood, horse-flesh, fish guano, 

 curds, &c. In the table showing the various articles of carp-food, I 

 have also given fresh red clover ; and I have done so because it is my 

 idea that if there is a clover field near the pond, clover may be used in 

 small quantities mixed with other food. If used in large quantities, 

 however, or by itself, it would not be found profitable, for, to return to 

 our example, to obtain 1,080 i)ounds of albumen would require 47,000 

 and 59,300 pounds of clover, respectively, which, at 2 jnarks [50 cents] 

 per 100 pounds, would cause an outlay of not less than 940 marks [$235] 

 and 1,186 marks [S296.50], respectively. 



In using this food we would, moreover, have to take into consideration 

 the fact— which applies to all articles of food which have to be given in 

 great masses, especially to the excrements of animals— that the dry 

 substance does not in the least come up to the proper standard of food, 

 and that such enormous quantities would have to be used as to make 

 it a matter of impossibility for the carp to consume them, simply to 



