THE NEW AET OF BKEEDING FISH. 93 



the umbilical vesicle which holds the remains of the 

 nutritive matter, analogous to the yolk of a bird's 

 egg, and at first by means of this substance the 

 minnows are nourished : but when absorption takes 

 place the young fish have need of other nutriment, 

 and should then be driven out of the box in which 

 they are cradled, and permitted to swim freely in the 

 streamlet which they are to stock. 



In fine, to procure for these little fish suitable 

 and abundant nourishment, it is only necessary to 

 leave or put in the water some frogs, whose spawn 

 they will greedily eat, while the tadpoles afford ex- 

 cellent food for the older trout. When the young 

 trout so brought up, are destined to stock a river, 

 they should be placed in streams tributary to it, and 

 water selected which rushes over pebbles or. rocks. 



In proportion as these fish grow, they descend 

 spontaneously to the deep water, whither they ar- 

 rive only when they are sufficiently agile to protect 

 themselves against the enemies which they may en- 

 counter ; while if they are at once placed in the 

 midst of other voracious fish, they will have but a 

 small chance of escaping death. When they are so 

 raised in streamlets or ponds, precaution must be 

 taken to separate the product of each year from the 

 former one, as the big trout will otherwise eat up the 

 little ones ; and to avoid this the young fish in the 

 same circle should be of one age. 



To establish after a regular fashion this branch 

 of production, there should be at least three stream- 



