BULLETIN OF THE UNITED STATES FISH COMMISSION. 455 



st; uces. For a person wlio needs but little of this food it may be 

 advantageous to manufacture it himself ; if lie does this, lie is not bound 

 to follow the receipt for my food as manufactured by Goos, but he ^vill 

 find in my article referred to above several receipts, and may make 

 different combinations based on my standard. There will be less doubt 

 of fish takin<^ kindly to this food than to that made according to Dr. 

 Harz's receipt. But persons who have to use the food in their ponds 

 hy the hundred-weight — and in preparing my food I principally looked 

 to feeding on a large scale, for which purpose the food should be made 

 so as to keep for a long time — will, I think, do decidedly better to buy 

 the food than to manufacture it themselves. It involves a considerable 

 outlay for nuichinery, implements, and labor. Leaving out of the 

 question the matter of expense, it will prove more advantageous to buy 

 tlie food, because the fish will then always get the same kind of food, 

 which is of some importance. A change of food is invariably followed 

 by a temporary decrease in the weight of the fish. 



I shall not follow Dr. Harz in his theoretical digression on the prac- 

 tical value of my food, as this would lead me too far ; and I will only 

 state in this connection what I said as early as 1879, in my work, " Agri- 

 cultural double book-keeping and its relation to the income of farms," 

 on page 30, on the practical value, which is of a relative character and 

 cannot, asE. Weiu does, be expressed in absolute figures, such as those 

 employed by Dr. Harz in his calculations. 



Briefly stated, the "practical value" of an article of food (or in fact 

 of anything) is represented by the net gain over its price, obtained by 

 using it, when it may be said to meet the requirements and circum- 

 stances of the buyer; while the " value of an article when bought" {an- 

 Icmfs icert) is a price which yields a net gain above the mere price paid 

 for it. This ap[>]ies to my fish-food, as I believe I demonstrated in the 

 article referred to, by figures, even if only ai^i^roximately. Proof of 

 this is furnished in Harz's article where he says " that the food has 

 found great favor, and enjo3^s an excellent reputation among practical 

 men." Dr. Harz finally thinks that he is rendering a great service to 

 fish culturists by recommending to them for fish-food a mixture of se- 

 same, lindseed-cake, and oats. As regards the qualitative chemical 

 combination Dr. Harz has followed my standard of fish-food, and noth- 

 ing can be said against him in this respect ; but I have serious doubts 

 whether trout will eat sesame and linsef d-cake, or oats. At least I 

 have never heard that they eat anything of the kind. It may be pos- 

 sible that carp will eat such food. It is therefore doubtful whether fish- 

 culturists when having my food and other kinds of food which have 

 stood a practical test will venture to experiment with it. 



Munich, Bavaria, May 20, 1884. 



