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 strugele. 
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 dise 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 apply 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 broken chela of a small Alpheus 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 sufliciently 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 sufficiently rapid as to wholly indraw the food before 
the crab would extend an ambulatory limb and vigorously abstract 
it. Im 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 stomodeum of the actinian and transfer it to its 
own mouth. 
The feeding experiments were sufficient 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 the dise of the actinian, or, rather, 
what determines the very definite responses of the chelipeds 
towards the dise 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 forth any responses 
on the part of the crab, It is most probable that the reaction is 
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