266 



SEASON 1878-79. 



winter was a very severe one so severe, indeed, that 20,000 trout 

 ova laid down in the Howietoun hatching-house on the 8th 

 November did not hatch till the 16th April, the incubation lasting 

 160 days. As eggs will stand much more crowding in cold than in 

 comparatively warm water, I could not have had a better oppor- 

 tunity to experiment. At this date nothing was known of the 

 power the pisciculturist exercises over the vitality of the embryo, 

 nor was the large amount of space demanded by the alevins as a 

 condition to their future existence recognised. 



I made deep boxes to fit into the 4 -feet rearing-boxes ; a level 



trough was built on to the deep box, 

 and a lead pipe fitted into the trough. 

 The edge of the deep box was kept 

 under the top of the trough ; a false 

 bottom of wood and perforated zinc 

 admitted the water into the deep box ; 

 some inches higher a grille was fixed to 

 FIG. 188 scale j. carry the eggs. A board was next 



fitted with flannel across the end of the rearing-box, 2 or 3 

 inches above the outlet screen. Water was admitted to the 

 rearing-box, and the deep box floated to its level. A hole was 

 then cut in the board to fit the lead pipe, which, when passed 



4' I' 



Fio. 189 scale J. 



through, held the end of the deep box in its place ; the other 



