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Puget Sound Marine Sta. Pub. Vol. 1, No. 11 



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PLATE 17 



Diagram of the arrangement of troughs and water supply. Troughs A and 

 D were painted black on the inside, while troughs B and C were painted white. 

 Troughs A and B receive independent supplies of water through pipes marked 

 I. T., each pipe having a stop cock by means of wliich the rate of flow could be 

 regulated. The w^ater TV'as conducted by means of pipes from the lower ends 

 of A and B to the upper ends of C and D respectively. 



The room containing the trough.s {Plate 17) was lighted by three 

 windows on the northeast and one on the southeast, those on the northeast 

 contained thirty square feet of glass and the one on the southeast nine 

 square feet. The troughs were placed quite close to the windows, the 

 relation being indicated in the diagram. No window-shades were used to 

 regulate the amount of light that fell upon the troughs. During the winter 

 months the sky was clouded for a considerable portion of the time and 

 not much light found its way to the hatching troughs. In addition to the 

 varying light of day, two 60-watt tungsten electric lamps were kept lighted 

 day and night throughout the period of observation. These lights were 

 provided with cup-shaped reflectors and for the first four months were 

 kept within one foot of the surface of the water in the sections of the 

 trough in which the fish were to be under the influence of light. After 

 this period the lights were raised to about four feet above the water. 



The water used was taken from that supplied to the City of Seattle 

 by the Cedar River. This water is of glacial origin and very pure. The 

 temperature varied with the season. Starting October 31, the date when 

 the eggs were placed in the hatchery, the water had a temperature of 

 13°C. It gradually lowered up to December 21, when the thermometer 

 registered 5°C., at which temperature it remained for about six weeks. 

 About this time it began to rise slowW and continued rising until it reached 

 a maximum of 21°C. in August. 



