414 H. BOSCHMA. 



Carpenter (1910) described the feeding reactions of Isophyllia. 

 The tentacles of this species catch small planktonic organisms. 

 When a certain amount of food is taken by the tentacles the 

 sphincter of the edge-zone of the oral disk contracts and the oral 

 disk then forms a kind of roof over the mouth and the surrounding 

 parts. In the superficial chamber formed in this way the di- 

 gestion of the food takes place. 



Vaughan (1912, 1919) studied the reactions to food in Mceandra 

 areolata and many other West Indian reef-corals. The food is 

 ingested through the combined action of ciliary movements, 

 secretion of mucus, and the movements of the tentacles. In some 

 species, e.g., in Orbicella cavernosa, the mesenterial filaments are 

 often protruded through the column wall and can catch food and 

 even digest it whilst remaining outside of the gastric cavity. 



With my feeding experiments on Astrangia I could confirm the 

 statements of former authors that it will readily take food in 

 captivity. When not overfed the polyps even will ingest almost 

 everything which is offered to them. The food-objects which I 

 used in my experiments were the following: crab meat (the 

 muscles of the legs of the spider crab, Libinia caniculata Say.), 

 fish meat, the soft parts of mussels, different species of worms 

 (e.g., Naraganseta coralii Leidy which lives burrowing in the 

 skeleton of Astrangia, Hydr aides and other polychset worms), 

 pycnogonids, small amphipods, larvae of higher crustaceans, 

 copepods, ctenophores, etc. Also juice of crab or mussel meat is 

 readily ingested. Besides these food-particles indigestible objects 

 are ingested by hungry polyps with the same avidity: coarse 

 sand, powdered writing chalk soaked in sea-water, clumps of 

 litmus, carmine and iron carbonate. 



When crab meat or fish meat is mixed with some coloring matter 

 (India ink, litmus, ammoniac carmine, neutral red) it is as readily 

 taken as pure meat. This method enabled me to trace the way of 

 the food in the internal organs after it had been ingested, the 

 coloring matter was only used as an indicator. 



These experiments with pieces of meat could not give results 

 which represent the normal feeding reactions. In the gastric 

 cavity of freshly collected specimens often remains of small 

 organisms are found, especially appendages of small crustaceans. 



