50 FISH CULTUEE. 



more than safe, as the slightest settlement of' only 

 the twenty-fourth of an inch, the shrinking of a 

 piece of woodwork, or the subsidence of brickwork, 

 may cause a leakage which it will be most difficult 

 to stop until the ensuing season, and may be a 

 constant source of annoyance. Cisterns should be 

 made of slate, if it can be conveniently managed — 

 not of metal nor wood, nor brickwork cemented. 

 Slate gives off nothing, will last for ever, and will 

 always fetch its value when you have no further 

 occasion for it, whereas the others are perishable, 

 worth nothing, are always dirty, and sometimes 

 slightly poisonous (to the fish). 



I have now described the best kind of apparatus 

 for sheltered work, and where the supply of water 

 is artificial. The best place to put such apparatus 

 in, is where the attendant can, when he desires 

 it, have plenty of light to see his work by in all 

 positions, and where it is alike defended from frost 

 and heat. Considerable cold retards the process 

 needlessly, and heat destroys the ova outright. Heat, 

 therefore, is the most to be guarded against of the 

 two. Sudden or great changes of temperature should 

 be guarded against, as they are hurtful The French 

 use brick sheds, well buUt. The Acclimatisation 

 Society has, to an extent, followed their example. 



