26 On Stocking. 



which fish-culturists, with the assistance of arti- 

 ficial redds, would take the fullest advantage. 



On the production of fry in the hatchery, I 

 cannot do better than quote from my History of 

 Howietoun, Part I., p. 57, line 13 : 



'The hatching-boxes are stripped of their fittings, 

 thoroughly cleaned, and the safety-screens fixed 13 inches 

 above the outlet. If the ova is on the point of hatching it 

 is then laid down on the wood. It is often convenient to 

 prepare the boxes a few days before the eggs are due to 

 hatch ; and since, if the eggs remained many hours in the 

 comparatively still water at the bottom, some of the embryos 

 would be drowned, a small piece of tile is laid in the box, 

 and a couple of grilles balanced on it until the hatch com- 

 mences, when the tile is taken out, and the grilles reversed 

 and removed. With 3 inches of water in the hatching-boxes 

 there is no danger of the alevins becoming suffocated a very 

 common source of loss in badly constructed trays. 



'A CO-OPERATIVE BREATHING SOCIETY. Shortly after 

 hatching the alevins congregate together in dense masses 

 in the corners and against the sides of the hatching-boxes. 

 If the water over these masses be slightly discoloured so as to 

 render visible the paths of the currents, small whirlpools will 

 be noticed descending over the apex of each mass, while from 

 the base the water radiates a thin swiftly-moving cloud. 



' On closer inspection it will be noticed the alevins are 

 lying with their heads approximately towards the apex, and 

 their paired pectoral fins working with remarkable rapidity ; 

 thus, instead of those lowest in the mass being in danger of 

 suffocation, they really receive the strongest water currents. The 

 mass is, in fact, a gigantic co-operative breathing association. 



* Very different is the fate of the unfortunate who finds a 

 refuge beneath the sheet of glass so frequently used in the 

 early days of trout-hatching to preserve the eggs from fungus. 

 In a very few hours a pale lifeless form marks the grave of 

 the suicide. Charred wood has abolished the necessity for 



