EXPORTATION OF FISHES AND HATCHING APPARATUS. 1011 



much better control of the eggs, aud some of them of the youug fishes, 

 than was possible with the earlier methods. 



The Holtou box, with the seventeen trays deep, as they are used, does, 

 perhaps, concentrate space more than any other form. The trays applied 

 in a long trough, containing apartments in which are inserted boxes 

 holding the trays, or nest of trays without the box, have, however, some 

 advantages, with the trays only seven or eight deep, the lower ones 

 are, of course, more accessible ; but it is after the hatching of the eggs, 

 when the care of the young fishes employs the attention of the cultur- 

 ist, that the great advantages of the compartments in the troughs ex- 

 hibit themselvies. The old way was to remove the fish to nursery tanks, 

 where they were put several thousands together, and where the surplus 

 of the food — liver, or curd, or whatever it might be — sank to the bottom 

 to decay and foul the water and sicken the young fishes. The com- 

 plaint was not uncommon that the fishes crowded in masses to where 

 the fresh water fell into the tanks and were at times seemingly 

 smothered. In the trough apparatus a box, having a wire-cloth bottom, 

 is inserted in each compartment, and the fishes, hatched upon the trays 

 of another box, are emptied into it. After a few days' feeding, in order 

 to cleanse the box containing the fishes, they are removed to a tray and 

 the box thoroughly washed. The larger pieces of curd or liver can bo 

 picked away from among the fishes, and they can then be returned to 

 the box until it is again necessary to repeat the operation. 



In the case of the California salmon, Mr. F. N. Clark, who used this 

 method in connection with his apparatus (see Keport of the United 

 States Commissioner, part II), finds that it requires nearly four times as 

 many of the boxes, open, to contain the living fishes as it does of the 

 eggs and embryos on the trays. Thus, while about forty-five hundred 

 to forty-eight hundred young embryos lie upon the seven trays within 

 a box, only about twelve or fifteen hundred young fishes should be put in 

 the same open box* where the fishes are fed. 



A very neat and convenient apparatus has been invented by Mr. T. 

 B. Ferguson, fish commissioner of Maryland. It consists of a simple 

 glass vessel, with an opening on one side, near the bottom, for the en- 

 trance of the water, and a smaller opening on the outside, near the upper 

 edge, for the escape. In the vessel is a series of nine or ten trays of 

 wire-netting, one above the other. The eggs lie on these trays and the 

 water passes upward through them to the place of exit, near the upper 

 edge. Several of these vessels can be combined by means of rubber 

 tubes, when the water, being introduced from a cock into the first, passes 

 through the entire series. Many thousands of eggs have been hatched 

 out by this means at the Druid Hill breeding establishment in Balti- 

 more. A description of the apparatus, with figures, can be found in the 

 report of the fish commissioner of Maryland, made to the house of repre- 



*Thc dimeusions of the box are about 14 inches by 9 inches, with a depth of 8i inches. 



