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BENJAMIN SCHWARTZ AND S. R. SAFIR 



preference for any side, whereas the fiddler crab had to over- 

 come a strong inclination. Viewed in this light the gains which 

 the animals made during the 10 days during which they were 

 tried are enormous. 



It should be mentioned that the possibility of establishing 

 pathways was obviated by either scraping off the top layer of 

 the substratum, or by adding a fresh one. Sight and touch 

 seemed to be the chief factors in the habit forming process, 

 the former predominating. It was observed that an animal 

 would often begin to go in the direction of the closed end, but 

 before approaching it, would turn and go in the opposite direc- 



FlG. 2. Showing labyrinth with alley. Dotted line represents glass 

 plates, and circles represent burrows. 



tion. This seemed to point to sight as the basic factor in the 

 habit forming process. 



. In order to test this hypothesis, another type of labyrinth 

 was devised. By means of glass plates, an alley, 10 cm. wide, 

 leading directly to the closed end, was made on one side of the 

 box. The glass plates which formed one side of the alley ex- 

 tended to within a distance of 8 cm. of the end of the box in 

 order that the crab might turn and avoid the blind corner. 



Five crabs which had given the best results with the laby- 

 rinth test, were made the subjects of the experiment. They 

 were tried for two successive days, being given ten trials per 

 day. Upon being liberated at the end of the alley nearest the 

 experimenter, the crab began to seek a means of escape. If 



