52 Modem Fishculture in Fresh and Salt Water. 



"NORTHVILLE, MICH., Jan. 21, 1899. 

 "Mv DEAR MATHER : I do not know how to describe 

 to you my reasons for using gravel in handling the 

 eggs of the Lochleven and the brook trout, other than 

 the fact that my motive is to employ the method which 

 will insure the largest percentage of eyed eggs, and by 

 the use of gravel we certainly have obtained better re- 

 sults. We use gravel only for the eggs taken from the 

 parent fish at this station, and then only until the eye 

 spots appear, when they are siphoned off the gravel and 

 placed on trays. By actual records at Northville, we 

 have met with from 10 to 15 per cent, greater loss by 

 placing the green eggs on wire cloth instead of on 

 gravel. What there is about the gravel which causes a 

 better percentage is more than I can tell. It may be due 

 to some chemical affinity between the wire trays and the 

 water here at Northville, producing a combination in- 

 jurious to the eggs, but it is certainly not imagination. 

 It is proven by actual records. Cordially yours, 



"FRANK N. CLARK." 



What Mr. Clark says about the water and the wire 

 trays reminds trie that at Cold Spring Harbor zinc- 

 lined waste troughs would be eaten full of pinholes in 

 one season by chemical action, while at other stations 

 zinc lasts a long time. 



PREPARING FOR HATCHING. 



Everything should be ready and the water running 

 through the troughs a week or two before an egg is 

 taken. Put in a horizontal screen at the head of the 

 trough one inch belcv/ its top. Let it be the width of 

 the trough and about 5 inches long ; lay it on cleats, or 



