248 KANSAS UNIVERSITY SCIENCE BULLETIN. 



While much has been done with the germ cells of other 

 hydroids, comparatively few workers have taken up Corymor- 

 pha. Weismann observed only a single female medusa of 

 Corymorpha, but describes this form in his "Die Entstehung 

 der Sexualzellen bei den Hydromedusen" (1883), and gives a 

 drawing to show ova in the ectoderm of the manubrium. He 

 finds the older ova in the manubrium, and describes germ cells 

 similar to the young ova among the ectodermal cells in the neck 

 of the manubrium. He finds the entoderm to contain no cells 

 that could be called germ cells, and concludes that the germ 

 cells arise in the ectoderm. Although he observed no male 

 medusa, he draws the conclusion that the male germ cells must 

 arise in the same way as the female cells in Corymorpha, since 

 they do in other allied forms. 



May* has described the morphology and development of 

 Corymorpha pendula, the eastern species, which differs from 

 Corymorpha palma, the western species, in only a few minor 

 points. He describes the general morphology of the form, 

 and takes up the development of the medusa. He finds the 

 medusa buds beginning as simple evaginations of the wall of 

 the peduncle. "By a proliferation of ectodermal cells at the 

 distal end of the bud, a plug of ectodermal cells is formed, 

 which grows down into the medusoid cavity forcing back the 

 entodermal cells as it advances." He states that these cells of 

 ectodermal origin give rise to the future reproductive elements, 

 but fails to show how and when definite germ cells arise, and 

 does not trace them through the early stages of development. 

 As the ova develop, certain cells are said to develop at the ex- 

 pense of others, by a process of absorption through pseudopo- 

 dia-like processes and by the breaking down of cell boundaries, 

 forming a syncytium of cells in which disintegrating nuclei 

 may be seen. 



Investigations by Torreyf indicate a third process, the in- 

 corporation of cells which have previously begun to disin- 

 tegrate. Torrey, in speaking of Corymorpha palma, says the 

 germ cells arise in the ectoderm of the manubrium from cells 

 which have been derived from the ectodermal plug, at the apex 



' May, Albert .1. 1903. A Contribution to the Morphology and Development of 

 Corymorpha pendula. The American Naturalist, Vol. :t7. No. 441. 



t Torrey, Harry Beal. 1907. Biological Studies on Corymorpha. II, Development of 

 C. palma from the Egg. University of California Publications. Zoology, vol. 3, No. 12. 



