AKTIFICIAL rONDS. 231 



possible with the water from which the ova, are 

 taken. In making experiments on the growth of 

 salmon-fry this precaution is more absolutely ne- 

 cessary than when one is breeding for the sole 

 sake of stocking a river. In all cases it will be 

 advisable that the spawning and rearing-ponds be 

 not fed with water of a temperature widely dif- 

 fering from that from which the spawn has been 

 procured. 



With these few general remarks I will trans- 

 cribe the notes I have received from Mr. A. Youns^ 

 on this interesting and important subject. To give 

 the seed, he says, the same advantages as that na- 

 turally spawned in rivers, the artificial breeding- 

 ponds should be erected in the immediate vicinity 

 of or in the river, and the ponds should be fed by a 

 small stream, or "lead" taken from the river, so 

 that the temperature and all the conditions of the 

 one may in every respect agree with those of the 

 other. At the spot you take the " lead" off the 

 river you commence the erection of a wall to 

 shut out the main current. The wall may be 

 built in the river by the side of one of its banks, 

 and its height then is to be greater than the 

 highest flood-marks of the river. In the bottom 

 of the wall, where it takes the " lead " off the river, 

 an opening or drain-mouth is to be constructed of 



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