GERM CELLS OF COELENTERATES 15 



Without repeating all the e\ddence presented in sections I and 

 II, the facts may be summarized as follows: there is no definite 

 place of origin of germ cells; there is no definite migration of 

 germ cells and no germ-track; there is no invisible germ plasm 

 in the body cells. Not only is there no continuous germ plasm, 

 so far as can be determined by observation, but the evidence is 

 such as to show the absence of invisible germ plasm. Hegner 

 ('14) is willing to admit the germ cells in Coelenterates do not 

 belong to any germ layer, but he maintains that germ cells are 

 present at all times in a dormant condition. This opinion is 

 based upon the conclusions of Downing, Wulfert, and Harm. 

 The error in the interpretation of these authors has been pointed 

 out and consequently the opinion that germ cells are present in 

 a latent condition at all times is no longer tenable; all the facts 

 are inconsistent with this view. 



b. Budding. Budding has generally been held to be a process 

 of growth and cell division, often an evagination taking place. 

 But Weismann says, ''. . . . I reached the conclusion, that 

 the budding idioplasm, which must be the starting point of the 

 budding process according to my view, could not be divided 

 between both germ layers, but probably was to be found in only 

 certain cells of the ectoderm. " At Weismann's suggestion, Lang 

 ('92) undertook to test this hypothesis and studied budding in 

 Hydra and some hydroids. Weismann believes Lang's results 

 ". . . . contain a perfect confirmation of my conjecture that 

 the same [buds] come from the ectoderm and that actually the 

 'Budding-idioplasm' had its position entirely in the ectoderm 

 cells." These quotations from the preface to Lang's paper 

 show the application made by Weismann of the germ-plasm 

 theory to this form of asexual reproduction. LLang believed his 

 results showed the proliferation of a few ectoderm cells to form 

 a mass from which the ectoderm and entoderm of the bud de- 

 veloped. After the two layers were formed, a cavity was pro- 

 duced in the bud, and this became continuous with the parent 

 enteronH Braem ('94) repeated the work of Lang on the same 

 and other forms, but could not confirm his results; on the contrary, 

 he observed the division of cells in ectoderm, interstitial, and 



JOURNAL OF MORPHOLOGY, VOL, 33, NO. 1 



