60 AMERICAN FISHES. 



A full account will be found, by those who desire to investigate tin 

 subject more thoroughly, in the Edinburgh New Philosophical Journal 

 for July, 1836, and January, 1838. 



Mr. Shaw, it seems, caused three ponds to be made, of different size, 

 at about fifty yards distance from a Salmon riyer, the Erith, the ponds 

 being supplied by a stream of spring-water, well furnished with the 

 larvae of insects. The average temperature of the water in the rivulet 

 was rather higher and less variable than of that in the river ; other- 

 wise the circumstances of the ova contained in the ponds, and of the 

 young fry produced therefrom, were precisely similar to those of the 

 spawn and fry in the river. 



These ponds were all two feet deep, with well-gravelled bottoms, 

 the highest pond eighteen feet by twenty-two, the second eighteen by 

 twenty-five, the third thirty by fifty. 



Observing two Salmon, male and female, in the river preparing to 

 deposit their spawn, Mr. Shaw prepared in the shingle, by the stream's 

 edge, a small trench, through which he directed a stream of water 

 from the river, and at the lower extremity of the trench, placed a large 

 earthenware basin to receive the ova. This done, by means of a hoop- 

 net he secured the two fish which he had observed ; and placing the 

 female, while alive, in the trench, forced her, by gentle pressure of 

 her body, to deposit her ova in the trench. The male fish was then 

 placed in the same position, and a quantity of the milt being pressed 

 from his body, passed down the stream, and thoroughly impregnated 

 the ova, which were then transferred to the basin, and thence to the 

 small stream which fed the upper pond, where they were covered up 

 in the gravel as usual. The temperature of the stream was 40°, that 

 of the river 36°. The skins of the Salmon were preserved, in order 

 to prevent the possibility of doubt or cavilling concerning the species 

 The male fish, when taken, weighed sixteen, the female eight pounds 



The result was, that the young fish were hatched, as I have stated 

 "n the scale above given. When first emerging from the membrane in 

 which it had been enclosed, with the yolk adhering to the abdomen, 

 the young fry is as it is shown in No. 1, of the cut referred to above. 

 The yolk is absorbed in twenty-seven days, after which the young 

 fish require nourishment. At the end of two months, the young fish 

 has attained the length of an inch and a quarter, as represented at 



