572 



EEPORT OF COMMISSIONER OF FISH AND FISHERIES. [106] 



laid down as a jjeiieral rule tliat, witliiu tliese limits the total (iiu.ntily 

 of efiective iintiitive matter being the same, i)rodnctiou will increase 

 as the proportion becomes smaller; but wliether in the end it will 

 yield greater profits will liave to be decided according to local circum- 



The proportion between albumen and hydrates of carbon will be par- 

 ticularly inauenced by the circumstance that in their food the anima s 

 should receive the quantity of hydrates of carbon which they absolutely 

 need for purposes of respiration. From experiments made by Mullcr 

 it appears that this .piantiry varies very much in the different animals. 

 Per 100 pounds weight of the body the tench exhales 12 grams carbon 

 = 1; the frog, 43.5=3.5; u.an, 110.0=12; the pigeon, 13-0. = 114. t 

 appears from these iigures that tish-in this case the tench, which greatly 

 resembles the carp in the quantity and quality of food it needs-use lor 

 the processes of life, more particularly of respiration, a very small ixn-- 

 tion of hydrates of carbon as compared with warm-blooded animals. 

 These figures, therefore, may serve as a guide in finding the luost suit- 

 able proportion of nutritive substances for fish. r>ut as no expenn.ents 

 have been made to test the matter, and as at any rate nothing has been 

 published on the subject, all that can be done is to draw conclusions 

 from analogv and compare therewith the experiments m feeding warm- 

 blooded animals. The exhalation of carbon h.dds a certain re at ion to 

 the absorption of oxygen. The more oxygen is absorbed the more 

 hvdrates of carbon will be destro>(>d. the greater warmth is generated 

 in the body, and the more carbonic acid is exhaled. But as fish have 

 no warmtirof their own, but always have the temperature of the water 

 in which thev live, they need only a small quantity of hydrates of car^ 

 bon to keep up life, and the result of Mr. Midler's experiments is proved 



true. . , 1 ,. • 



Althou.-li it is impossible to iind out from these experiments what is 

 the proportion between the quantities of carbon inhaled and exhaled, 

 it is safe to assume that the greater the quantity consumed in the res- 

 piratorv process, all the more hydrates of carbon will have to be intro- 

 duced into the body with the food, and vice verm, l^auss.ngault^s ob- 

 servations throw some light on the proportion between the quantity ot 

 carbon in the food and that consumed by the respiratory process m 

 domestic animals. It appears that the milch-cow and the horse exhale 

 00 per cent, the hog 70 per cent, and the pigeon SO per cent ot the car- 

 bon absorbed with the food. These data, however, do not yet answer 

 our purposes, and we have to look further. Experiments made at 

 Wende with full-grown sheep have shown that these animals, while 

 receiving 481.3 grams carbon with their food, exhaled 222.5 grams (*_«., 

 60 per cent) per 100 pounds of live weight in twent y-four hours .t The 



*Prof. E. Wolti", FUUcruugslchre, 1H74, v- 14'. 



tProf. E. Wolff, Fiitterung der landwirihschaftlichen Nutztkiere, 1874, p. 3o. 



