44 FISH HATCHING. 



that from those left to their natural course 

 there would not have been so many fecun- 

 dated eggs from the 310 as we have in the 

 breeding-boxes from the forty fish. All 

 these fish were caught on one ford where the 

 Almond joins the Tay." 



Then again, we have the reverse of floods 

 we have droughts ; and the nests made 

 when the water is high become bare and 

 exposed to the air when the water goes 

 down ; either the eggs die from this cause, or 

 else the young when hatched out, having no 

 water, " refuse to exist." 



I have seen a shallow ditch leading out of 

 Ruislip Reservoir one mass of dead fry of 

 roach, dace, and jack, the water having been 

 let out for the canal. 



Nor must we forget mill-wheels. Here is 



