FEEDING REACTIONS IN CORAL POLYPS. 423 



cysts. The mesenterial filament then consists of a marginal, 

 glandular part and a part with digestive function next to the 

 marginal part. Morphologically, however, the word "mesen- 

 terial filament" usually is employed in a more restricted sense, 

 meaning only the marginal, glandular part (cf. Schneider, 1902). 

 Also Duerden (1902), who states that the swollen part of the 

 mesentery next to the marginal region is generally considered to 

 be the principal seat of digestive function, denotes the marginal 

 region only as the mesenterial filament. I use here the term in 

 the same sense as other authors who studied digestion in antho- 

 zoans, and differently from the definitions of Schneider and Duer- 

 den. The glandular part of the mesenterial filament contains 

 the bifurcation of the mesoglcea. It is sharply separated from the 

 digestive part by a deep furrow; the digestive part is, as in other 

 madreporarians (cf. Duerden, 1902), not sharply separated from 

 the rest of the mesentery, usually its thickness is slightly more. 



In my studies on the digestion of Astrangia I chiefly used 

 pounded crab meat thoroughly mixed with some coloring matter 

 which served as an indicator after the food had been swallowed. 

 A number of small colonies served as material for each experi- 

 ment. I noted the time of feeding and studied the changes in the 

 internal organs at various intervals by cutting open a polyp and 

 examining a mesenterial filament under the microscope. 



In the case of crab meat colored with India ink the food is 

 readily taken by the tentacles and transferred to the mouth. 

 Then it slowly descends through the stomodaeum into the gastric 

 cavity. By the transparency of the tissues it remains visible in 

 the lower part of this cavity, where it is in contact with the 

 mesenterial filaments. The polyps gradually expand more or less 

 and often rise considerably above the skeleton (to about 15 mm., 

 the tentacles also may stretch to the same length). When, after 

 a very short time, the food is ingested into the mesenterial fila- 

 ments these organs are visible as dark stripes through the wall of 

 the polyps. Already one hour after feeding the digestive part of 

 the mesenterial filament is crowded with small black spots (the 

 particles of India ink) which indicate that the food with the 

 coloring matter has been ingested here. Sparsely distributed 

 black particles are also often found in the adjoining portion of the 

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