272 Proceedings of the Royal Physical Society. 



pursued, I took into consideration how it could best be carried 

 out. In stocking rivers with trout and salmon, good results 

 are often obtained by depositing eyed- ova in either natural 

 or artificial redds. The advantages of depositing eyed-ova 

 over newly fertilised ova are (1.) that the water in the redds 

 often contains a quantity of mud, which, though harmless 

 to the fry, is fatal to the eggs during the early stages of their 

 development ; (2.) that owing to the variations in the 

 temperature of the water passing over the redds, the embryos 

 when hatched are often so feeble that they are incapable of 

 surviving ; (3.) that owing to the protection afforded during 

 the earlier stages, the number of fry hatched is likely to be 

 greater. 



In the case of the herring there is practically no risk from 

 impurities in the water, and the number of ova obtained from 

 each female herring being so great the destruction of a con- 

 siderable number by fish, etc., is not a matter of any moment, 

 and this destruction is limited compared with the salmon, as 

 they are often hatched in ten or twelve days, and are seldom 

 over forty days in hatching. Hence, all that is required is, 

 that a sufficient number of fertilised eggs should be deposited 

 on the spawning ground. At first it seemed that this would 

 be easily accomplished by dropping stones, etc., coated with 

 eggs on the bank, but on finding that the eggs were apt to 

 be destroyed when this was done, and that the gravel-coated 

 portions of the bank were always selected by the herring in 

 preference to others, I devised a simple apparatus for con- 

 veying the egg-coated stones safely to their destination. This 

 apparatus is in the form of a galvanised iron tray about 20 

 inches in diameter and about 4 inches in depth, with a bottom 

 consisting of two portions hinged to a central bar so as to 

 open outwards. This tray is provided with four cords, two 

 attached to the rim and one to each half of the false bottom. 

 When loaded with stones which may be coated with eggs on 

 both sides, the tray is deposited, all the four cords being held 

 tight until it reaches the bottom. On reaching the surface 

 of the bank the cords attached to the false bottom are set 

 free, while the other cords are drawn up, the result being that 

 the two halves of the bottom open outwards leaving all the 



