102 Thirtieth Ammal Meeting 



of the sheets and tacked on the frame. Where the lines cross, at 

 right angles, a hole is made with a six-penny wire nail, from the 

 inside of the screen. Thus in a screen of ten by twenty inches, 

 inside measurements, there will he 200 holes. In driving the 

 nail through the tin a shallow dent or depression is made around 

 each hole, while on the under side the hole has a ragged or broken 

 edge. 



The simple driving of the nail produces just the conditions 

 that are needed. The water naturally gravitates into the ninhili- 

 cated margins of the holes, and passing through, is broken up by 

 the ragged edges below, imprisoning the air as it falls into the 

 trough. We thus have 200 l)roken streams of water, the most 

 efficient system of aeration that can be devised, and the most 

 sim]3le. Where the screen is made of the perforated zinc or tin 

 of the shops, the water pours through but a portion of the lioles, 

 as before mentioned, and moreover has a tendency to cling to the 

 smooth under surface of the screen bottom, until the water from 

 several holes coalesces, and by its added weight finally drops 

 into the trough in streams of unequal sizes. This condition of 

 affairs is patent to any one who has interest or curiosity enough 

 to examine into it. 



I consider the commercial perforated zinc or tin a delusion 

 and a snare for any purpose whatever in fish culture. For foot 

 or guard screens it clogs, for reasons before given, and the smooth 

 round holes are a constant temptation for fry to worm themselves 

 through, whereas by using brass wire cloth the flow of water is 

 free and unol)structed, and fry are not so apt to attempt to pass 

 through it, and would fail to do so if the mesh is small enough. 



FEEDING FRY. 



I wish to call particular attention to the remarks of ]\Ir. W. 

 T. Thompson on the subject of feeding fry, which may be found 

 in the proceedings of this society for 1900, pages 143-146. 1 

 wish to indorse and emphasize what he says concerning the feed- 

 ing of fry before the yolk-sac is absorbed. I first adopted the 

 plan of feeding grayling fry as soon as hatched several years ago, 

 and afterward trout fry in a similar manner. My plan is to 

 feed the bloody water from finely ground and screened liver, by 

 placing it in the horizontal aerating screen at the head of the 



