Abstract
During the summer of 1922, certain observations and experiments were made at the Woods Hole Laboratory of the Bureau of Fisheries that add to our ability to interpret the behavior of fishes in the field.
Ten fish at a time, males of the species Fundulus heteroclitus, about 9 centimeters in length were placed in each of twin troughs 10 feet × 4 1/2 inches × 4 inches, with glass plates at the ends and with a middle intake at the bottom and the outlet under a glass plate which could be changed in position.
The troughs were conspicuously marked off in feet and records of the position of the fish were taken at intervals of 15 minutes during the course of the experiments. The records were for example—2 P. M. 6 (fish) at 4 (feet from illumination); 4 at 7.
Light adaptation was secured by means of a 200 watt Mazda light suspended above the troughs; while dark adaptations were accomplished by leaving the fish overnight in running water, available in the troughs at all times, or by the use of light proof shades for shorter periods of preliminary adaptation.
Light stimuli were applied by means of two 40 watt Mazda lights of equal intensity, placed in twin lamp houses, which like the troughs, were blackened inside and outside and which were equipped with rectangular slits, 1/2 inch in width and 2 inches in length, so that light could be directed in a narrow beam through the clear glass ends of the troughs or through the Eastman monochromatic filters that were sometimes interposed.
The experiments to be here recorded are as follows:
I. Temperature uniform, current stopped 15 minutes prior
1. Dark adaptation 12 hours (over night), room darkened, light stimulus applied for 10 trials at left and 10 trials at right of trough.
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