546 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



years of experimenting, but methods were perfec'ted that made their 

 production as certain and with losses nearly as small as in other species. 



The necessity of production of immense numbers in attempting to 

 multiply the market species of fishes established the fact that the 

 apparatus used in trout-hatching had to be extended over a wide area 

 to accommodate them. The culture of the white fish and the salmon- 

 trout induced modifications of apparatus at the New York State hatch- 

 ing establishment. 



In 1872 wire-cloth trays were introduced within the troughs, placed 

 one abo%^e another, four in depth. These trays were made of double 

 lath on the sides and single on the ends, so that the current in the 

 troughs passed through the narrow spaces at the ends, washing both the 

 upper and lower sides of the wire-cloth on which the eggs were placed. 

 A large supply of water was afforded each trough. The ordinary bed 

 of gravel remained at the bottom of the troughs, in which the young 

 fish were allowed to rest and hide themselves during the greater part 

 of the yolk-sac period. 



This apparatus was in some respects superior to that of 0. Gr. Atkins, 

 in the fact that it not only afforded facilities in manipulating the eggs, 

 but afforded economy of space. 



In 1872, at the New York State hatching-house, a new device was 

 invented (perfected in 1873) by Marcellus G. Holton, of Seth Green's 

 staff, to obviate the defects of the ordinary graveled troughs, and even 

 of the improved trough. The arrangement of wire-cloth trays within 

 troughs afforded a ready manipulation of the eggs, and a better oppor- 

 tunity for removing sediment and the omnipresent confervoid growth, 

 {Achlya prolifera,) but did not afford in a sufiScient degree the great 

 desideratum of economy of space. 

 , This apparatus (see plate) consisted of an outside case or box of wood, 

 with a pipe conducted from a reservoir of water into the bottom, and 

 the top of the case being below the source of supply, the water, of 

 course, filled and overflowed at the top ; within this case a series of 

 wire-cloth trays were fitted, placed one above the other, from seven 

 to eighteen in a case ; and in the largest size not more than eighteen 

 inches square, and containing about 18,000 white-fish eggs to the tray, 

 so that in a space about 4 feet in width by 8 feet in length, 2,000,000 of 

 white fish may be hatched, while at the very least twenty-five of the 

 ordinary graveled troughs would be required for this number of eggs, 

 filling the space of a very large hatching-house. 



In 1873 a device to accomplish like results was made by Mr. N. W. 

 Olark, of Clarkston, Mich., and patented in 1874. (See plate.) 



This arrangement employed the troughs, but divided them into com- 

 partments by means of water-tight partitions or bulkheads 5 into each 

 compartment a box containing a series of trays filled with eggs is placed 

 and covered with a pan of perforated tin, upon which the water falls 

 and descends through the i^erforations upon the screens and eggs be- 



