American Fisheries Society 157 



thrust in a bit-hole in the side of the fry tank, making a 

 water-tight joint, about an inch of the hose projecting on the 

 outside and the longer part on the inside of the tank. To 

 the inner or longer end the cage and bag are attached in the 

 regular manner, this being accomplished by lifting the end of 

 hose above the water surface of tank. More than one dis- 

 charge is provided for a tank to allow for renewal of strainer 

 bags while the tank contains fry. The rigidity of the hose 

 holds the strainer away from the sides and bottom of the 

 tank, where fry sacs would otherwise be crushed. As the 

 outer end is fixed and an open orifice, the head of water in 

 the tank is inevitably fixed at a given point, and is necessarily 

 constant. 



Thus, it will be noted that in the jar the customary dis- 

 charge tubing is discarded, and in the fry tank the siphon 

 feature and siphon cup are eliminated — a simplification in 

 apparatus and the attainment of ideal results. 



The tank head at the beginning of the season was 4 feet 

 and 4 inches, afterward, almost unavoidably, increased to 5 

 feet and 2 inches. Another season I would reduce the tank 

 head to 3 feet or less, for the avoidance of free air in tlie 

 rul)ber and glass tubing connecting the jar with the water- 

 piping, the free air being a phenomenon that is encountered 

 every season when the greatest number of eggs are in the 

 hatchery. Spawning, occurring at 69 to 70 degrees, takes 

 ])lace on a marked rise in temperature that is usually continu- 

 ous for some days, and is attended with the free liberation of 

 air from the water to a bothersome extent, slowly and almost 

 imperceptibly charging the feed tubing of the jars with free 

 air to the extent of reducing the flow of water and causing 

 the eggs to become matted if neglected long. But it is not 

 the matting of the eggs that gives greatest anxiety, rather is 

 it the difficulty in actually keeping the flow of water up to the 

 standard and yet not wash the eggs out of the jar. When 

 there is air in the rubber tube and the petcock is correctively 

 opened far enough to restore the inadequate flow in a jar, the 

 attendant may have gone but a few feet away when it is dis- 



