2 GEORGE T. HARGITT 



Eudendrium is a common Tubularian hydroid of our Atlantic 

 coast; it is also widely distributed in other parts of the world. 

 The reproductive cells are developed within simple, more or 

 less sac-like, gonophores which in the mature animals seem to 

 have few, if any, of the characteristic structural features of 

 polyps or of medusae. However, such gonophores (often called 

 sporosacs) are commonly referred to in discussions and in text- 

 books as degenerate medusae or medusoid buds, and it is this 

 assumption of the degenerate medusoid character of the gono- 

 phores which is mainly responsible for certain interpretations of 

 the germ-cell history of Eudendrium which I believe are errone- 

 ous. It is only necessary to point out that the female gono- 

 phores, at least, arise from, and by the modification of, a hy- 

 dranth or polyp which, in the beginning, resembles in structure 

 other polyps of the colony. Since this may easily be demon- 

 strated by a study of the developing reproductive bodies, it is 

 manifestly quite incorrect to speak of the female gonophores of 

 Eudendrium as medusoids, and any discussion, phylogenetic or 

 otherwise, which proceeds upon such a basis is, of course, quite 

 futile and meaningless. While I have not given the same at- 

 tention to the method of formation of the male gonophores, it 

 may be doubted whether these have any more of the medusoid 

 character than do the female gonophores. 



Ciamician ('78), studying Eudendrium ramosum, decided the 

 egg cells arose from the ectoderm of the gonophore itself. His 

 figures clearly show that he distinguished the egg cells only 

 after they had become of some size, and his conclusions do not, 

 therefore, touch the question of the real place and method of ori- 

 gin. Kleinenberg ('81) came to the conclusion that the egg 

 cells arose in the ectoderm, passed into the entoderm, and mi- 

 grated into the gonophore, where they again entered the ecto- 

 derm and completed their growth and development. Weismann 

 ('83), in his study of E. racemosum, found egg cells in the ecto- 

 derm and entoderm, but, since those in the ectoderm were always 

 smaller, concluded this layer was the place of origin. The re- 

 gion of the colony concerned in the formation of the eggs was 

 the stem just below the terminal hydranths. He accounted for 



