1014 REPORT OF COMMISSIONER OF FISH AND FISHERIES. [6] 



portion of nutritive substances could only be obtained if pure meat-flour 

 was used ; (III) that the cost of the food was too high compared with 

 the results obtained. 



We have already shown that the quantity of food is not too small, but, 

 if anything, too great, and this has been proven by the experiments 

 made, to the entire satisfaction of every one, except my critic. 



The assertion that a quantity of food which is enough for that animal 

 which is well known to need the greatest quantity of food, is not suffi- 

 cient for fish, especially for carp, is so entirely at variance with the 

 organism of flsh, their powerful digestion, &c., that, if scientific re- 

 searches ever prove the necessity of modifying my standard of food, the 

 modification will certainly not consist in increasing the quantity of food, 

 especially of albumen; although, on the other hand, I will not deny 

 that there is a possibility that a larger proportion of the nutritive sub- 

 stances may be found to be better adapted to the purpose. 



It is possible that as fish, compared with land animals, have very 

 little demand for oxj'gen, a much larger portion of the hydrates of car- 

 bon, and of the fat received by the body — because not burned for the 

 purpose of producing the heat of the body — is, instead of being expelled 

 from the body as useless, utilized in the formation of flesh and fat. Too 

 great a quantity will, therefore, act less injuriously on the utilization of 

 the proteine, received with the food, than in land animals. We should 

 not, however, be justified from this circumstance in drawing the conclu- 

 sion that a larger proportion of nutritive substances than that found by 

 me would be the most favorable and profitable proportion for the carp. 

 It is doubtful whether sufficient light will ever be thrown on this sub- 

 ject by direct experiments on carp, because this would require a com- 

 plete collection of all the excrements, and their chemical analysis, which, 

 with fish, would be an exceedingly difficult matter, considering the fact 

 that no way has as yet been found to make a complete collection of all 

 the solid and fluid excrements of a domestic land animal like the hog. 



All the experiments in feeding known to me have yielded higher 

 results than the calculations based on my standard of food — 0.7 kilo- 

 gram of albumen for 1 kilogram of fish flesh. 1 think that this was 

 caused by the circumstance that, in mixing the food, I calculated the 

 digestible albumen and the hydrates of carbon (according to Prof. Em. 

 Wolff) which were produced by the digestion coefficient {verdaungs- 

 coefficimten) for the land animals, whilst it is well known that carp pos- 

 sess a much greater power of digestion and ability to extract than 

 land aninuils. In using my standard of food this would only prove the 

 calculations not exact, by increasing the profit, but not by diminishing 

 it; and this would cause, not an increase, but a decrease of the stand- 

 ard nutritive substances. 



These and similar thoughts rise in my mind in connection with this 

 subject ; but I am of opinion that all such considerations may be left 

 to the investigation of specialists. 



