THE ACTIVITIES OF CORYMOEPHA 305 



A fairly well marked constriction separates the stalk from 

 the hydranth. The hydranth consists of a thickened disc 

 attached to the distal end of the stalk and carrying on its pe- 

 riphery some twenty to thirty long tentacles, the proximal ten- 

 tacles. From the middle of the outer face of the disc rises the 

 proboscis, at the distal end of which is the mouth surrounded 

 by about forty to sixty short tentacles. Immediately beyond 

 the bases of the proximal tentacles, and taking their origin 

 from the proximal part of the proboscis itself, arises a number 

 of short peduncles, to which are attached fixed medusae bear- 

 ing the gonads. The appearance of Corymorpha as a whole is 

 that of a delicate miniature palm whose substance seems to be 

 translucent glass rather than animal matter. 



The common reaction systems possessed by the majority 

 of coelenterates are the mucous glands, the cilia, the nettle 

 cells, and the muscles. In many coelenterates, as for instance 

 the anthozoan polyps, the mucous glands are extremely impor- 

 tant and provide abundance of secretion, whereby the column 

 of these animals is protected and their foot and tentacles are 

 rendered adhesive. In Corymorpha, on the other hand, the 

 mucous glands are insignificant. The tentacles of this form 

 are scarcely if at all adhesive and the other parts of its body are 

 not especially slimy. Mucus, therefore, plays little or no part 

 in the economy of Corymorpha. 



It is also doubtful whether there are any cilia in this hy- 

 droid. Torrey makes no mention of these bodies in his de- 

 scription of the exterior of Corymorpha and a most careful 

 search under the microscope with carmine suspended in sea- 

 water as an indicator has failed to reveal to me the least sign 

 of cilia on the stalk, proboscis, proximal tentacles, peduncles 

 of the fixed medusae, or the distal tentacles. 



The longitudinal canals of the stalk when studied in a liv- 

 ing specimen under the microscope are seen to contain a fluid 

 carrying many minute particles of one kind or another. These 

 particles are in almost continual motion and Torre}' ('04 a, 

 p. 417; '05, p. 334) believed that this motion was caused not only 

 by changes of pressure due to variations in the muscular activity 



