AN ESTABLISHMENT OF ASSOCIATION IN HERMIT 

 CRABS, EUPAGURUS LONGICARPUS. 



By E. G. Spaulding, Ph. D. (Bonn). 



College of the City of New York. 



Introductory. 



The experiments described in this paper are the result, 

 first, of preliminary observations of a number of hermit crabs 

 kept for some time in an aquarium at the Woods Hole Labora- 

 tory, which showed them to be quite capable of profiting by 

 experience. In fact, the results first obtained were in general 

 quite confirmatory of those obtained by the subsequent more 

 systematic investigation, the method for which they indicated. 



Bethe ^ and Yerkes^ have each made experimental studies 

 of habit formation in the Crustacea, the former on the crab, 

 Carcinus moenas, the latter on the crawfish, Cambams affinis, and 

 on the green crab, Carcinus gramdatiis. BETHEatthe end of his 

 paper relates some experiments made to determine whether or 

 not the crab possesses psychical processes, with the result that 

 he asserts that it does not. This conclusion is not, however, 

 necessarily to be accepted even from Bethe's own experiments, 

 for the reason that these at best serve to demonstrate the ab- 

 sence of only one kind of psychical phenomena, viz., those of 

 inhibition or control ; other kinds may be present. Bethe 

 himself does not recognize that the method he employed was 

 defective in this respect, but an account of it will, we think, 



' Bethe. A., Das Centralnervensystem von Carcinus moenas. Archiv f. 

 mikr. Anai, Bd. 51, 1898. 



' Yerkes, Robert M. and Huggins, Gurry E. Habit Formation in the 

 Crawfish, Cambarus affinis. Harvard Psychological Studies, Vol. I. 1903. 



Yerkes, Robert M. Habit Formation in the Green Crab, Carcinus gran- 

 ulatus. Biolog. Bulletin, Vol. HI. 1902. 



