174 H. C. STEVENS 



a tactile stimulus may initiate the decorating response. There 

 is, however, no evidence to show that the tactile stimulus is 

 the only stimulus adequate to produce this response. Whether 

 visual stimuli alone may initiate such responses is as yet unde- 

 termined. Complete tactile anaesthesia would be necessary 

 with vision unimpaired. Such an experiment is technically 

 feasible and ought to be made forthwith. 



Four crabs were used in this experiment. Specimen 7, a 

 female, was blinded VIII-21-12 by cutting off the eye stalks 

 close to the orbit by means of a pair of scissors. The animal 

 was then placed in the aquarium. It manifested considerable 

 restlessness by moving about the walls of the aquarium. It 

 assumed a position in one corner of the aquarium from which 

 it refused to move for some time. On VIII-28-12 this indi- 

 vidual was found to be gaily decorated with ulva. These deco- 

 rations were removed completely and on the next day, VIII- 

 29-12, the animal was observed to be again decorated with 

 seven or eight pieces of ulva which had been placed upon the 

 legs and back of the carapace. The animal was observed from 

 time to time until IX-6-12 when it was found to be covered 

 with polysiphonia with only two pieces of ulva on the legs. 

 The polysiphonia had been placed in the aquarium VIII-27-12. 

 No other crab made use of this material for decoration. The 

 polysiphonia was removed from this individual IX-6-1 2 . Noth- 

 ing had been added by IX-8-12, 12:30 P. M. The animal died 

 IX-9-12. 



Specimen 26, a young female, was blinded IX— 7— 12 at 4 

 P. M. by cutting off the eye stalks with a pair of scissors. All 

 foreign material was then stripped off from the carapace and 

 legs by means of a pair of forceps. Immediately following the 

 operation the animal was very restless and made no attempt 

 either to feed or to decorate itself or to preen. There was no 

 decoration IX-8-12. On IX-9-12 the animal was observed to 

 be covered with pieces of ulva and polysiphonia. The ulva was 

 removed from the rostrum. A few minutes later the animal 

 was observed to place a flag of ulva 18 mm. by 6 mm. on the 

 rostrum after "mouthing" it. The animal was observed to 

 feed on dead clam. On IX-10-12, 2:30 P. M., the animal was 

 observed in the act of decorating itself. The manner of decora- 





