758 PROCEEDINGS OF THE AMERICAN ACADEMY. 



products of metabolism destined for other than enzyme use. Food 

 material may be taken into these cells, and even algae have been found 

 in them in a partially digested condition. Some of the food, then, is 

 probably digested here, both in an intra-cellular and extra-cellular 

 fashion. After the remaining food passes the stomodaeum it is in 

 contact with the six ventral mesenterial filaments. These (Plate 4, 

 Fig. 64) are very short thickenings of the margins of the six mesen- 

 teries, and occupy a position immediately below the stomodaeum. 

 They are less than two millimeters long and in preserved material 

 may be less than one. The}' begin at the deep end of the stomodaeum, 

 but their gland cells may be found on the mesenteries a little above 

 this. The cross section shows that this thickened margin is nearly 

 cylindrical. The cells are mostly gland cells that are not different 

 from the granular cells of the stomodaeum. A few supporting cells 

 occur among the others and these may contain food matter. There 

 are no nettle cells. 



Until 1899, the stomodaeum was considered as merely a passage 

 for the food, the mesenterial filaments being regarded as the only 

 digestive organs. Wilson ('84) described the filaments of eleven 

 genera from the three groups of Alcyonaria and concluded that the 

 six lateral and ventral filaments are derived from endoderm and that 

 the two dorsal ones are from ectoderm. The former contain gland 

 cells and sometimes nettle cells, and are digestive in function; while 

 the latter have two kinds of cells, are ciliated and are used for the pro- 

 duction of currents. In 1899 Ashworth found mucous gland cells 

 in the stomodaeum of Xenia, and correlated their presence with the 

 absence of the ventral filaments. Miss Pratt ( :05), by a very thorough 

 and complete study of the feeding, in which she employed colored food, 

 found that food was ingested, not only b^^ the cells of the stomodaeum 

 and filaments, but also by the mesogloeal cells. But no ingulfing of 

 food was observed in the cells containing the granules. Gland cells 

 were abundantly present in the stomodaeum of many members of the 

 Alcyonaria, but the granular cells were met with in starved individuals 

 only. Pseudoplexaura agrees with the forms studied by Pratt in the 

 presence of gland cells in the stomodaeum and the abundance of the 

 granular cells in the tips of individuals starved in filtered sea water. 

 In Miss Pratt's experiments particles of fish artificially colored were 

 also engulfed by stomodaeum cells, by the network of interstitial cells 

 in the polyp wall, and by the mesogloeal cells near the outer surface 

 of the coenosarc. Both the stomodaeum and the ventral filaments, 

 then, are digestive structures; while the granular gland cells, which 



