No. i.] 



STUDIES UPON HYDROMEDUSAE. 



47 



tion as a new outgrowth, there being only the slightest traces of 

 pigment present. The growth was quite gradual, and not until 

 about August 14 had it become fully formed and functional. 



In each case there had also been regenerated additional 

 radial canals, as indicated in the figures. These appeared 

 in connection with the lines of union, and were not at first 



FIG. 19. 



suspected as canals. Later the deposition of pigment along 

 their course pointed strongly to the conclusion that they were 

 canals, though whether yet functional I am not able to say. 



In none of my experiments has there been any clear con- 

 firmation of the results and conclusions of Bickford ('94) that 

 in Hydroid regeneration the polyp, tentacles, etc., are produced 



Fie;. 20. 



simply by a "transformation of the tissues of the stem " -that 

 is, that the tentacles are formed by a sort of longitudinal 

 cleavage of the coenosarc, and a remolding of it directly, 

 without any tissue changes. In cases where there is only a 

 recasting of a portion of the body into the form of the original, 

 as in the case of a Medusa divided into sections, where each 



