378 BULLETIN OF THE UNITED STATES FISH COMMISSION. 



prime condition — none otherwise — and it several times occurred that 

 female salmon were a second time committed to the inclosure and 

 yielded a second litter of eggs. The growth of the salmon during 

 their absence had been very considerable, there being always an in- 

 crease in length and a gain of twenty -five to forty per cent, in weight. 

 The conclusion seems unavoidable that the adult salmon do not enter 

 the Penobscot for spawning oftener than once in two years. 



The method of impregnation employed has alwaysbeen an imitation 

 of the Eussian method introduced into America in 1871. The eggs are 

 first expressed into tin pans, milt is pressed upon them, and after they 

 are thoroughly mixed together, water is added. The result has been 

 excellent, the percentage of impregnated eggs rarely falling so low 

 as 95. 



After impregnation the eggs are transferred to the hatchery at Craig's 

 Pond Brook, where they are developed, resting upon wire-cloth trays in 

 wooden troughs, placed in tiers ten trays deep, to economize space, and 

 at the same time secure a free horizontal circulation of water. 



The hatchery is fitted up in the basement of an old mill, of which 

 entire control has been obtained. The brook is one of exceptional 

 purity, and a steep descent within a few feet of the hatchery enables 

 us to secure at pleasure a fall of 50 feet or less. The brook formerly 

 received the overflow of some copious springs within a few hundred 

 feet of the hatchery, which so affected the temperature of the water 

 that the eggs were brought to the shipping point early in December, 

 an inconvenient date. This has been remedied by building a cement 

 aqueduct 1,600 feet long, to a point on the brook above all the springs, 

 which brings in a supply of very cold water. 



The shipment of eggs is made in January, February, and March, 

 when they are sent by express, packed in bog-moss, all over the northern 

 States, with entire safety, even in the coldest weather. 



In the following statement is embraced a general summary of the 

 results of each season's work : 



Tear. 



1871-72.... 

 1872-'73.... 

 1873-'74.... 

 1874-75.. .. 

 1876-'76.... 

 1879-'80.... 

 1880-'K1 .... 

 1881-'82..-. 

 1882-'83.... 



Total 



d 

 % 



% 



S 



111 

 692 

 650 

 601 

 460 

 264 

 622 

 513 

 560 



4,373 





P. 



GO 



Cj 



a 

 © 



n 



225 

 279 

 343 

 237 

 19 

 227 

 232 

 256 



1,829 



3 

 ■§ 



00 



bB 



1, 5G0, 



2, 452, 



3, 100, 

 2, 020, 



211, 



1, 930, 



2, 690, 

 2, 075, 



071 



(Mill 



638 



479 

 000 

 692 

 561 

 600 

 000 



10, 118, 941 





a 



to 



70, 500 

 241, 800 

 291, 175 

 842, 977 

 825, 000 

 200, 500 

 841, 500 

 611, 500 

 000, 000 



14, 924, 952 



