PROPAGATION AND DISTEIBUTION OF FOOD FISHES, 1922. 95 



space between the bottom and sides of the outer receptacle 1 and the 

 bottom of lower tray 3, this body of water can move only by virtue 

 of the air space 8 between the sides of the outer receptacle 1 and 

 lower tray 3, with the result that a portion of the water will be forced 

 up into the air space 8 with considerable violence and pressure by the 

 mass movement of the body of water in the lower part of the outer 

 receptacle and will pass in small jets from the space 8 into the lower 

 traj^ <?, not only through the perforations 7 in its sides, which are 

 below the normal surface of the water, but also through the per- 

 forations 7 which are above the surface of the water, falling there- 

 from through the air into the lower tray 3 and becoming aerated 

 by its passage through the air. 



The amount of water thus forced into the lower tray 5, will, be- 

 cause of the pressure to which it is subjected, be somewhat greater 

 than the quantity which will flow out by its own weight through 

 the limited number of perforations 10 below the surface, with a result 

 that the level of water in the lower tray will be raised somewhat 

 above the level of the water in the outer receptacle until a point is 

 reached where the area of the perforations submerged by the water 

 within the lower tray 3 is sufficient to compensate for this forced 

 injection. In this way a higher level of water is maintained within 

 the lower tray 3^ which affords the fish greater freedom of action 

 while the container is in motion. 



^'\Tien the container is stationary, the water level within the lower 

 traj^ 3 immediately returns to its normal level to be determined by 

 the character of fish to be shipped. For example, in shipping large 

 fish as distinguished from fry, the water should be of sufficient depth 

 to permit the fish to swim about with their dorsal fins exposed 

 above the surface. The fish then assist in the aeration of the water. 



When the supply of oxygen in the water becomes depleted, the fish 

 begin to feel discomfort, which manifests itself in increased activity 

 on their part and results in the splashing about of the water because 

 of its extreme shallowness. 



The upper tray 11 acts as a cover and baffle plate whenever the 

 motion of the container is sufficient to cause the water to splash 

 against it. The perforations H in the bottom of the upper tray 11 

 are of such dimensions that the water can not pass through in suffi- 

 cient volume or with sufficient force to slop over, but will percolate 

 back into the bottom tray 3^ becoming aerated in the process. 



The upper tray 11 also serves as a receptacle for supporting ice 

 when considered necessary; as, for example, when shipping cold- 

 water fish, such as trout, in extremely hot weather. The perforations 

 IJf, permit the ice water to drip into the bottom tray 5, carrying with 

 it a large supply of oxygen. Under such circumstances the outer 

 flap 18 of the absorbent jacket 16 is drawn over the ice and retained 

 in position by fastening means, such as drawstrings 21. 



The bottom 9 of the tray 3 is shown slightly dished and perforated 

 at its lowest point, the center 10. The excrement of the fish settles 

 to the bottom of the tray 3 and passes through perforations at the 

 center 10 into the lower part of the container where it settles and 

 remains on the bottom because of the comparative stillness of the 

 water in that part. 



34223°— 23 7 



