AETIFICIAL HATCHING OF SPAWN. 43 



these slates having holes bored with a coarse drill 

 (about three to the inch), in order to deposit the ova 

 one in each, much after the fashion of the racks used 

 to hold shot on board a ship of war. It was merely 

 an experiment ; but as there was no advantage in it, 

 beyond being able to tell the exact number of eggs, 

 and it was rather a trouble than otherwise, added to 

 which, the salmon ova, being large, stuck somewhat 

 firmly in the holes, and it was difficult to dislodge 

 them, I do not by any means recommend it. The 

 French use a glass grille, or gridiron, made of glass 

 tubes, placed closely side by side, and inserted into 

 wooden frames at the end ; on these the eggs are 

 placed (see cut in description of Huningue, p. 9). These 

 grilles are set up in small earthenware troughs, some 

 two feet long and six inches wide, which are well 

 glazed on the inside. I highly approve of the glazing, 

 and think the earthenware troughs thus prepared, 

 preferable to slate, and the glass certainly offers less 

 hold to confervas than any other substance. Excellent 

 as these devices may be, and no doubt are, after 

 much consideration I do not think that man's in- 

 vention surpasses nature, and I am firmly of opinion 

 that the best plan to adopt is to place the ova under 

 the gravel, more particularly where much deposit is to 

 be apprehended. If you want to inspect the ova by 



