VALUE OF NORWEGIAN LAKES FOR FISH CULTURE. 589 



perature of their blood, and compensate for the wear and tear occasioned 

 by constant motion, the cold-blooded transform nearly all their food to 

 an increase of their own size, and grow, therefore, in proportion thereto, 

 without using more than a small quantity for maintaining the low tem- 

 perature of their bodies, and to compensate for the small wear and tear 

 occasioned by their little motion. It is therefore a mistake to feed fishes 

 with the flesh of warm-blooded animals, unless it is entirely worthless 

 offal, because it is contrary to natural economy. Cattle can be fed up 

 and fattened only by a liberal use of the natural means of nourishment, 

 whose i^rocuring demands considerable employment of human labor, 

 whereby a comparatively large portion is used without corresponding 

 increase in growth, wkile fish, left to themselves or fed in a i)roper man- 

 ner, will consume what in itself costs nothing, and what could not in 

 any manner be utilized. They should, indirectly or directly, be fed 

 from the water's domain, whose crop practically is left to i^erish, with- 

 out at jjresent being useful for men. Neither is the flesh of the inhabi- 

 tants of the water, when it can be obtained, less valuable for men than 

 that of land animals. Pound for i30und, it contains the same quantity 

 of nourishment and will sustain human life just as well, while under cer- 

 tain conditions it is more profitable. It gives the brain and the nerves 

 phosphorus, which is not contained in all kinds of food, but which is 

 just as essential to complete health as gluten or starch, while it at the 

 same time is so much more easily digested than the flesh of land animals 

 and birds that it is used as a modified form of fasting, and at certain 

 times of the year is more wholesome than the last-named kinds of food. 

 A wise economy of the means of nourishment which nature gives will, 

 therefore, as the population increases, compel us to turn our attention to 

 the harvest which the water can yield." 



Y. 



ESTEMATED PROFIT AND THE ECONOMICAL VALUE OF THE WATER- 

 AREA. 



I shall next, with the guidance which the foregoing results of expe- 

 rience furnishes, attempt to show what i>rofit one may expect from fish 

 culture in our rivers and lakes, if this business in the future is attended 

 to with the care which is now bestowed upon the prosecution of an in- 

 dustry of corresponding importance, and this everywhere in proportion 

 to the opportunities offered by more or less favorable conditions for the 

 necessary attention to the business. 



From the examj)les cited is seen what also lies in the nature of the 

 business, that this culture can be carried on in very different ways, alike 

 by artificial rearing and complete feeding in apparatus and basins spe- 

 cially constructed therefor through the whole time which intervenes 

 before the fish can reach the development one desires ; also, by what one 

 might call perfect stall-feeding, by inconsiderable cleanings out in the 



