32 NATURAL HISTORY OF THE SALMON. 



opened and the young fry admitted, and that is 

 generally done in the end of May. When the 

 fry are liberated from the lower canal, they spread 

 themselves over the pond, and into whatever part 

 of it the keeper throws the food, they may be 

 seen rising to it in great numbers. This pond is 

 the most faulty part of the whole plan ; it is only 

 223 feet long by 112 feet wide at its broadest 

 part, and is far too small to contain and nourish 

 300,000 fry, which the boxes can hatch ; it would 

 require a pond of four times the size to rear the 

 produce of the boxes; besides, another pond is 

 necessary for enabling the hatching to be carried 

 on every year. There is a slight current in the 

 pond; but we think not so great as it should be, 

 to supply abundant fresh water for so many fish. 

 At the lower end of the pond there is a pipe, 

 for the purpose of emptying it, connected with a 

 drain to the river. When artificial propagation 

 is more in favour than it is at present with our 

 salmon proprietors, all these evils will be remedied. 

 We have said that the gravel for the hatching- 

 boxes should be well cleaned, dried, and exposed 

 to the action of the sun and air, in order to rid it 

 of the larvae of insects, the greatest enemy the ova 

 have, which statement we shall illustrate thus : 



