XX.—REPORT OF OPERATIONS CONNECTED WITH THE PROPA- 
GATION OF WHITEFISH (COREGONUS ALBUS) AT THE NORTH- 
VILLE STATION, NORTHVILLE, MICH., FOR SEASON OF 1880-81. 
By FRANK N. Cuiark, in charge. 
PREFACE. 
A brief notice of the hatchery, together with its immediate surround- 
ings and facilities for the work under consideration, may properly pre- 
cede an account of the work of the season. 
The Northville hatchery was built by the late N. W. Clark, its nucleus 
being collected from a similar establishment formerly located at Clarks- 
ton, Mich., thirty miles distant. The latter building was torn down and 
removed, together with the appurtenances of fish-hatching contained 
therein, to its present site during the summer of 1874, and the erection 
of a building double the size and capacity of its predecessor immediately 
begun. 
A description of the hatchery as then completed and of its surround- 
ings will suffice in the present instance, as no material changes were 
made until August, 1880, at which time the United States Fish Com- 
mission assumed control. Under their direction many needed improve- 
ments have been made and some new features added, which will be 
noticed in the proper place. The hatchery as built and as it now 
remains, is a one-story frame structure, 80 feet in length by 30 in width, 
containing a 9 by 11 office in front, also an 8 by 30 tank-room in the 
rear. Its interior arrangements were designed more especially for the 
accommodation of the hatching appliances to be used therein, viz: hatch- 
ing troughs and the “Clark” hatching box. No new apparatus was 
introduced, neither was its capacity increased previous to the present 
season. The main or hatching room was provided with three parallel 
tanks, each 50 feet in length and uniformly 9 inches in depth. One tank 
was 42 and either of the others 28 inches in width, the larger being 
divided into 96 and each of the others into 64 compartments for the 
reception of the boxes, making a total capacity of 224 hatching boxes. 
Although as many as 75,000 eggs of the whitefish can be brought for- 
ward successfully in each of these boxes, usually but 48,000 have been 
incubated therein, it being possible to hatch a greater percentage with 
less trouble and expense when the latter number is not exceeded. Of 
the éggs of Salmo fontinalis or Salmo iridea not more than 24,000 should 
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