2 



SALMONII>.E. 



two, the second eighteen feet by twenty-five, and the third 

 thirty feet by fifty, were prepared at a convenient distance 

 from a Salmon river, (the Nith,) the ponds two feet deep, 

 thickly embedded with gravel, and supplied from a small 

 stream of spring water, in which the larvae of insects were 

 abundant. The distance from the river to the ponds is 

 stated as rather less than fifty yards, a proximity, it is ob- 

 served, " sufficient to place the young fish confined in them 

 on a similar footing with those in the river, so far as situa- 

 tion is concerned. The average temperature of the water is 

 also nearly the same in both ; that of the rivulet, however, 

 being rather higher and less variable than that of the Nith.*" 

 The experiments were conducted with great care. The 

 ponds being prepared, the next object was to secure the fish, 

 the progeny of which were to form the subject of observation. 

 " With the view, therefore, of securing two Salmon, male 

 and female, while engaged in the performance of the act by 

 which the species is propagated, Mr. Shaw provided himself 

 with an iron hoop five feet in diameter, on which he fixed a 

 net of a pretty large mesh, so constructed as to form a bag 

 nine feet in length by five feet in width. The hoop and net 

 were then attached to the end of a pole nine feet long, thus 

 forming a landing net on a large scale. The weight of the 

 net with its iron hoop being upwards of seven pounds, it in- 

 stantly sunk to the bottom when thrown into the water." 



" Being thus prepared with the means of carrying his ex- 

 periment into execution, Mr. Shaw proceeded to the river 

 Nith on the 27th January 1837, and readily discovered a 

 pair of adult Salmon depositing their spawn. Before pro- 

 ceeding to take the fish, he formed a small trench in the 

 shingle by the edge of the stream, through which he directed 

 a small current of water from the river two inches deep. At 

 the end of this trench was placed an earthenware basin of 

 considerable size, for the purpose of ultimately receiving the 



