128 THE CANADIAN NATURALIST. [April, 



Supposing tlie eggs to have been properly laid in their nests, 

 they become the prey of pests innumerable. The larva of the may- 

 fly and the dragon-fly justly called the river-tiger) act the same 

 part to the fish-eggs in the water as do the hedgehogs and other 

 vermin to the pheasant-eggs on land. 



Among birds the fish-eggs have many enemies as well as friends. 

 The chief of the former are common ducks, which, with their spade- 

 like bills, soon get all the eggs out of the nests and devour them. 

 The swans, though very graceful ornaments in a pond, do a deal 

 of mischief to the fish, especially in the Thames. Two birds, the 

 water-ouzel and dab-chick, have been accused as poachers after fish- 

 eggs. I have examined the crops of several of these birds, and have 

 invariably found them to contain the remains of insects, but no fish- 

 eggs. This matter was fully discussed at the Zoological Society, 

 and the verdict first arrived at was '' not proven," and on second 

 consideration the water-ousel was fully acquitted from the charge 

 of eating spawn. True it is he is ever feeding upon the spawning- 

 beds ; he goes there to eat the insects that are devouring the eggs, 

 but he himself does not touch them at all. 



The moor-hens, however, I am pretty sure, will eat the eggs 

 of the fish. A good observer tells me that one morning the moor- 

 hens got to his hatching-boxes and cleared all the eggs out of them. 

 There is another bird which does a good deal of harm to the fish- 

 hatcher. A friend writes to me to say that he has killed several 

 king-fishers under the wires where his fish were confined. Herons 

 also are terribly destructive to the fish in the spawning-beds. 



We have seen what becomes of the fish's eggs if they are left 

 to themselves. It is necessary, therefore, for man to interfere, and 

 take the eggs from the fish and keep them under his charge. In 

 ail matters of interference with nature, we cannot do better than 

 take nature herself as a guide. We observe that the fish makes her 

 nest of her own accord in a rapid, shallow, and gravelly stream. 

 We therefore must put the eggs in an artificial nest where the fol- 

 lowing requisites are present : a stream more or less rapid ; gravel ; 

 darkness; and perfect quiet. This stream must be allowed to 

 run over the eggs perpetually, day and night, until the yo jng fish 

 are hatched out, just as it would do in the brook. 



At the piscicultural establishment at Haningue, in France, the 

 eggs are placed upon glass rods, such as I now show you, during 

 the time of incubation. I would however most humbly beg to 



