82 SALMONIA. 



rently no food ; but, after about a week, the 

 nourishment in their bag being exhausted, they 

 began to seek their food in the water, and 

 rapidly increased in size. As I have said before, 

 Mr. Jacobi assures us, that the experiment 

 succeeded as well with mature fish, that had 

 been killed for the purpose of procuring the 

 roe and melt, these having been mixed to- 

 gether in cold water immediately after they 

 were taken out of the body. I have had this 

 experiment tried twice, and with perfect suc- 

 cess ; and it offers a very good mode of in- 

 creasing to any extent the quantity of trout in 

 rivers or lakes ; for the young ones are pre- 

 served from the attacks of fishes, and other 

 voracious animals or insects, at the time when 

 they are most easily destroyed, and perfectly 

 helpless. The same plan, I have no doubt, 

 would answer equally well with grayling or 

 other varieties of the salmo genus. But in 

 all experiments of this kind, the great prin- 

 ciple is, to have a constant current of fresh and 

 aerated water running over the eggs. The 

 uniform supply of air to the foetus in the egg 

 is essential for its life and growth ; and such 



