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OUT OF DOORS. 



thousand ova. As, therefore,, the percentage of un- 

 hatched eggs is extremely trifling when they are in 

 proper condition, this single set of troughs can turn out 

 about thirty thousand young fish at a single hatching. 



An experiment has been successtuUy tried to sub- 

 stitute slabs of slate for the gravel, the plates being 

 exactly one foot long and seven inches wide, so that 

 three will precisely fit into each trough. The plates 



EGG, PRY, AKD PAKK. 



are covered with cup-like hollows, much resembling the 

 little pits in a ' solitaire ' board : a small hole is pierced 

 quite through the centre of each, so as to permit water 

 to pass freely. Each plate contains one thousand of 



