48 Modern Fishculture in Fresh and Salt Water. 



"Now, entering into each of these angles from the 

 outer trough is a hole with a gate, by which the flow 

 of water may be regulated. * * * The idea is to 

 introduce currents of water at intervals along the en- 

 tire length of the trough in such a way that the fish 





TROUGH FOR YOUNG SALMON. 



will find a number of places with the conditions they 

 prefer, instead of the single one at the head of the ordi- 

 nary trough. * * *." 



Mr. Seal gives no explanation of the letters used in 

 the diagram. As I understand it they are as follows : 

 BB, troughs ; F, wood or metal angles ; W, wire gauze. 

 If the inner trough could be made to sit so flat on the 

 bottom that no little heads could wedge under it, this 

 plan would be good. There is no record of the use of 

 such a trough. 



WHY DO WE USE COAL TAR? 



That is a very proper question, and to answer it I will 

 have to tell a story. Raw white pine troughs put in the 

 hatchery and fed with water soon begin to exude a jelly. 

 I have taken sheets of it from the bottom and sides that 

 were J of an inch thick. This is a form of turpentine, 

 and it will kill trout eggs and embryo trout, every one 

 of them. When I visited the Caledonia hatchery in the 

 spring of 1868, the troughs were lined with 10x12 win- 



