WATER FOE TROUT CULTURE 91 



culturist more work, for if the water at the 

 end of that time warms appreciably, the eggs 

 are apt to hatch almost simultaneously. 



Limestone, otherwise called hard water, is as 

 good for trout-breeding as soft, although, in 

 some circumstances, more prone to encourage 

 fungus, unless it should, as sometimes happens, 

 contain an overplus of organic matter. A little 

 iron in the water will not prove harmful, but 

 some mineral substances are undesirable, and 

 in large quantities fatal; for example, a sul- 

 phur impregnation is likely to prove hurtful, as 

 also is very much iron. 



A limestone spring may prove dangerous 

 apart from its mineral qualities for a reason 

 unsuspected by those who have not had expe- 

 rience with one of that type and its possible 

 vagaries. This danger is the liability of the 

 underground stream which feeds the spring to 

 suddenly change its course, abandon its outlet 

 and seek another. A change of this kind may 

 occur as the result of an attempt to raise the 

 body of the spring by damming it, thus increas- 

 ing the weight and pressure on the channel 



