34 Modern Fishculture in Fresh and Salt Water. 



ture requires. In such an operation as I have described 

 not over ten per cent, of the eggs are fertilized, because 

 the milt fails to reach them, and not two per cent, hatch 

 and live until they are ready to take food. 



We beat nature in hatching fish as we do in growing 

 corn or cotton. We impregnate 95 per cent, of the eggs 

 and raise about 80 per cent, of the hatch, because we 

 protect both eggs and young from all enemies. 



In order to make up for infant mortality the cod, the 

 eel and some other fishes lay many millions of eggs, 

 seemingly to provide food for other aquatic life, just as 

 plants provide seeds for birds and mice and still enough 

 escape to keep up the species. The fewer the casualties 

 to which a race is exposed the smaller the number of 

 eggs or young which it needs to produce in order to 

 cover the necessary losses. In fish generally it takes at 

 least a hundred thousand eggs each year to keep up the 

 average of the species. In frogs and other amphibians, 

 a few hundred are amply sufficient. Reptiles oftenilay 

 only a much smaller number. In birds, which hatch 

 their own eggs and feed their young, from ten to two 

 eggs per annum are quite sufficient to replenish the 

 earth. Among mammals, three or four at a birth is a 

 rare number, and many of the larger sorts produce one 

 calf or foal at a time only. In the human race at large, 

 a total of five or six children for each married couple 

 during a whole lifetime makes up sufficiently for infant 

 mortality and all other sources of loss, though among 

 utter savages a far higher rate is usually necessary. 



EGGS OF TROUT. 



Eggs of the trout are comparatively few in number 

 and of large size. They vary more than the eggs of any 



