1905.] BEARING ACTINIANS IN THEIR CLAWS. 505 



actinians remained altogether passive without even retracting ; 

 sometimes the points of the maxillipeds would penetrate the 

 delicate flesh of the polyps and be freed only after a struggle. 



By far the most unique and remarkable reactions were those 

 observed when the actinians were supplied with food. When 

 shreds of meat were placed on the disc of the polyp, the latter 

 responded in the usual manner of actinians by bending its ten- 

 tacles towards the disc and partly closing over the food. If the 

 pieces were too large to be wholly covered and readily ingested, 

 the crab seemed to be soon aware of their presence, and would 

 then bring forward the hook of one of the first ambulatory limbs 

 and appl}^ it to the oral disc from time to time until all the 

 fragments of food were removed and transferred to its own 

 mouth. Thus the freshly bi-oken chela of a small Alphceus was 

 placed upon the oral disc of the actinian so carefully as not to 

 touch any part of the Melia. Immediately the polypal tentacles 

 closed over it preparatory to ingestion, but before the process was 

 accomplished the first ambulatory limb of the crab reached over 

 among the tentacles and dragged away the fragments to its own 

 mouth. 



If the fragment were sufiiciently small as to rest wholly on the 

 disc of the polyp, and the latter quickly opened its mouth to 

 swallow it, the Melia might then exhibit no responses and the 

 actinian appropriated the food. But in very few instances in a 

 number of feeding experiments were the ingestion reactions of 

 the actinian sulficiently rapid as to wholly indraw the food before 

 the crab would extend an ambulatory limb and vigorously abstract 

 it. In some instances the fragments were already partly swallowed 

 by the polyp when the crab, receiving some stimulus, would extend 

 an ambulatory limb to the polypal disc, and actually abstract the 

 food from the stomodaeum of the actinian and transfer it to its 

 own mouth. 



The feeding exjMriments ivere sufftcient to demonstrate beyond 

 all question that Melia actually takes away and appropriates to 

 itself the food procured by the actinian. In the language applied 

 to human actions, it can be truly said that the crab robs the 

 actinian of its food, though no one would think of introducing 

 ethical considerations into the act, even if consciousness could be 

 established. 



What are the means by which the crab is made aware of the 

 presence of food-material on tlie disc of the actinian, or, rather, 

 what determines the very definite responses of the chelipeds 

 towards the disc of the actinians ? It is certainly not a tactile 

 reaction, for the responses took place when the food-particles 

 could not possibly have come into contact with the crab or any 

 of its tactile organs. It may have been that the movements of 

 the polyp during ingestion produced some stimulus which was 

 transmitted through the chelipeds, but ordinary stimulation of 

 the actinian by mechanical means failed to call foi-th any responses 

 on the part of the crab. It is most probable that the reaction is 



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