Mr Shaw's Experiments on the Fry of the Salmon. 167 



covered drain to the distance of 20 feet from the pond. The 

 water of the whole is then left to find its way to the river. 



To prevent any communication arising from an accidental 

 overflow of the ponds themselves, I have raised embankments 

 upon the intersecting walks of 2 feet in height, so that the se- 

 veral families of fish which the ponds contain can have no ac- 

 cess, direct or indirect, to each other. Where the rivulet is 

 divided for the purpose of supplying the several ponds, I have 

 formed an artificial fall in each stream, of a construction to pre- 

 vent the fish from ascending one stream and descending an- 

 other. Finally, where the water discharges itself from the 

 ponds, the channels are so secured by wire-grating that it is 

 as impossible for the young fish to escape as for any other fish 

 to have access to them. The whole occupies an area of nearly 

 80 feet square. 



My experimental basins being prepared, my next object 

 was to secure the fish, the progeny of which were to form the 

 subject of experiment. With the view, therefore, of securing 

 two salmon, male and female, while in the very act of propa- 

 gating their species, I provided myself with an iron hoop 5 feet 

 in diameter, on which I fixed a net of a pretty large mesh, so 

 constructed as to form a bag 9 feet in length by 5 in width. 

 I then attached the hoop and net to the end of a pole 9 feet 

 long, thus forming a landing-net on a large scale. The weight 

 of the net with its iron hoop being upwards of 7 lb., it instantly 

 sunk to the bottom on being thrown into the water. 



Being thus prepared with all the means of carrying my 

 experiment into practice, I proceeded to the river Nith on the 

 4th January 1837, and readily discovered a pair of adult sal- 

 mon engaged in depositing their spawn. They were in a si- 

 tuation easily accessible, the water being of such a depth as to 

 admit of my net being employed with certain success. Before 

 proceeding to take the fish, I formed a small trench in the 

 shingle by the edge of the stream, through which I directed a 

 sn^U stream of water from the river 2 inches deep. At the 

 end of this trench, I placed an earthenware basin of consider- 

 able size, for the purpose of ultimately receiving the ova. I 

 then, at one and the same instant, enclosed both the fish in the 

 hoop, allowing them to find their way into the bug of the net 



