42 PRACTICAL TROUT CULTURE. 



a combination of the two. The cut on the oppo- 

 site page, representing the Trontdale hatching- 

 house, in 1868, will show the trough arrangement. 



In the floor are set two double rows of wooden 

 troughs, thirty feet long by eighteen inches wide 

 and four inches deep ; these are each subdivided 

 by cross-pieces of wood into twenty compartments, 

 18x18 inches, the bottoms of these divisions be- 

 ing covered to the depth of about an inch with 

 fine white gravel, and a gentle current of wattT 

 allowed to flow through them, the water being 

 carefully filtered. In fact, no unfiltered water 

 should be allowed to enter any hatching-house ; 

 not only so-called dirt (which has been prop- 

 erly defined as misplaced matter) will enter, but 

 also the larvae of insects, many species of which 

 destroy the spawn with tremendous rapidity. At 

 Stormonfield, Scotland, over seventy thousand 

 salmon eggs were lost in one season from this 

 cause. 



When, from the location, it is possible, it is well 

 to have the troughs raised breast-high, that in ex- 

 amining the spawn and removing the dead a back- 

 breaking position may be avoided. This, in our 

 old hatching-house, was unfortunately impossible 

 the fall from the spring to the level of the floor 

 being but a few inches. Short troughs have been 

 much lauded by writers, but after careful experi- 



