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OTTO C. GLASER 



the road to food and comfort; indeed, in nature there are many 

 problems whose solution must be accomplished at once with the 

 utmost rapidity, and to the swift alone is the race. 



METHODS 



The animals used were white rats of different ages, and the general 

 method, a modification of the time-honored labyrinth. Instead 

 of the usual form, however, I constructed a zinc tank, 2 feet, 1 

 inch square, and 6 inches deep, and covered it with coarse-mesh 

 zinc netting, in the exact center of which a circular opening, 

 fitted with a cylindrical shoot, serves as an entrance for the ani- 

 mals. At each of the four corners the cover, which is firmly 

 clamped to the sides of the tank, has a small hinged door that 

 can be opened at will, or made fast, likewise by means of clamps. 



Fig. 1. Tank. Photograph by Miss Frances Dunbar. Dimensions 2 feet 1 inch 

 square: depth, (i inches; diameter of funnel. 4 inches; height of funnel, 6 inches; 

 exits. ;; inches square. 



