HATCHING APPARATUS. 55 



stone, slate, pottery, metal, wood with glass lining, glass 

 grilles, and charcoal, or carbonized wood. I think ex- 

 perience will finally reduce the number in general prac- 

 tice to two, namely, glass grilles and carbonized wood. 



Wood in its natural state is out of the question, for 

 the fungus that it grows wholly unfits it for hatching. 

 I venture to say that hundreds of thousands of eggs 

 have been destroyed by the fungus coming from wood- 

 en troughs. Metal, whether in the form of screens 

 or anything else, will not do, because the absorbing 

 power of trout eggs is so great, that, if placed in con- 

 tact with it, they will in time absorb enough metallic 

 matter to destroy them.* 



Slate, pottery, and soapsto'ne answer very well, but are 

 all expensive ; and if an expensive article is used, glass 

 grilles, I think, have the preference over everything else. 



For cleanliness, tidiness, and convenience they are 

 not surpassed by anything. Their expense is their 

 only objection. Charcoal troughs, on the other hand, 

 are equally as effective as grilles, and infinitely more 

 economical. They are also more accessible, more 

 simple, and more durable. 



In estimating their comparative merits I should say 

 that the glass grilles are the thing for the rich man's 

 experiments, and the carbonized troughs are the thing 

 for business ; I cannot but think that the carbonized 

 troughs will supersede everything else, where trout- 



* Fourteen trout eggs were placed on a copper-wire screen, in 

 November, 1869, at the Cold Spring Trout Ponds, and in fifty- 

 days they had absorbed so much copper that they were of a 

 dark brown tinge, and hard like peas. 



