PISCICULTURE IN CRYSTAL PALACE. 85 



which smothers the ova, Dr Esdaile suggests dispensing 

 both with boxes and gravel, and depositing each egg in 

 a little cup punched in either a plate of zinc or in a 

 slab of coarse stoneware. Why not of strong coarse 

 glass, which is now cheap, and in which small hollows 

 could easily be made for the separate reception of each 

 ovum ? In about three feet square he calculates on 

 depositing 20,000 ova, at a very trifling expense. In 

 order that our readers may have a choice of fish-breed- 

 ing apparatus, we advise them to examine that used by 

 M. Coste, whose treatise on pisciculture, translated by 

 M. De Valmont, and published by the enterprising Mr 

 Thomas Ashworth, may be had of Simpkin, Marshall, 

 and Co., London. 



The public interest in the artificial rearing of salmon 

 will, we hope, be increased by the process being wit- 

 nessed in that wonder of wonders, the Crystal Palace. 

 Being at Sydenham on a visit to a piscicultural friend, 

 we joined in persuading one of the Crystal Palace direc- 

 tors that a salmon-breeding apparatus would be an 

 attractive addition to the instructive contents of the 

 Palace. Our friend, moreover, volunteering to supply 

 the ova from Tay salmon, the offer was accepted ; and 

 in the Crystal Palace there soon was a model river, 

 stocked with ova of salmon in process of being devel- 

 oped. Contrary to our friend's wishes, it was placed in 

 the tropical department. As might have been foreseen, 

 the excessive heat was most injurious. Instead of 

 being in a temperature of about 40 Fahr., they had to 

 endure one of about 60 Fahr. The temperature of 

 fishes is from 2.7 to 3.6 higher than that of the 

 medium in which they live ; * so that we were not 



* Liebig's ' Letters on Chemistry,' p. 67. In order to prevent 

 unnecessary pains to protect salmon ova from the effects of cold, 

 it should be known that, if gradually applied, it does not injure 

 them, and that they have been known to be frozen up in a sheet 

 of ice without losing their vitality. R6aumur demonstrated that 

 the eggs of many insects are equally uninjured by excessive cold. 



