968 SUMMARY OP CURRENT RESEARCHES RELATING TO 



differences, however, are almost certainly of secondary origin, and due to 

 the early development of the tentacles. It is impossible to place Cunoc- 

 tantlia in any one of Hackel's four families of the Narcomedusse ; the great 

 German naturalist placed it with the Cunauthidse, but, as it has no canal- 

 system at all, it belongs rather to the Solmarid^, from which, however, it 

 is distinguished by the possession of otopupse. In the shape of the true 

 umbrellar edge it belongs to the Peganthidse. The difficulties raised by 

 this form, as by Gunina prohoscidea, which Metschnikoff has shown to have 

 otoporpse and canals when produced from a fertilized egg, and no otoporpse 

 or canals when produced asexually, compel us to acknowledge that Hackel's 

 classification is so far unsatisfactory. 



Origin of Male Generative Cells of Eudendriura racemosum.* — Mr. 



C. Ishikawa has investigated Eudendrium racemosum with the object of 

 seeing whether the theory of Prof, Weismann that all sexual cells in the 

 Hydromedusse were primitively of ectodermal origin is correct. He finds 

 that, in the males, the young germinal cells which are found in the endo- 

 derm of quite young gonophores, attached to the supporting membrane, are 

 really derived from the ectoderm. In some fortunate sections the author 

 was able to find the young on the outer side of the supporting membrane, 

 lying in the ectoderm ; in later stages they had disappeared therefrom, and 

 were only found in the endoderm. 



A young blastostyle of E. racemosum already carrying a number of 

 gonophores with ripe sperm-cells exhibits the following appearance in 

 transverse sections : in sections taken through the base of the gonophores 

 groups of small rounded primitive germ-cells were found partly lying 

 directly on the supporting membrane, and partly deeper among the endo- 

 dermal cells. Nearer the base of the blastostyle (but still in its capitulum) 

 sections reveal the presence of these cell-groups not only in the endoderm, 

 but also in the ectoderm, where they lie directly on the supporting mem- 

 brane. They are exactly similar to the primitive germ-cells found in 

 the endoderm, and the author thinks there can be no doubt that they are 

 primary male germ-cells which have not yet made their way into the endo- 

 derm. Mr. Ishikawa is not, however, able to say whether all the male 

 cells are differentiated in the blastostyl from the ectoderm, and whether 

 some are not formed in the stalk of the hydranth, from which the blasto- 

 styl is developed. 



Polyparium and Tubularia.t — Dr. A. Korotneff gives a full account of 

 the remarkable Polyparium amhulans, the preliminary description of which 

 we have already noticed.^ The following is the author's opinion as to the 

 systematic position of this peculiar form. 



The chief characters are the absence of tentacles, the presence of 

 various oral cones which lead into a common cavity, but have no oesophageal 

 tube, the apparent absence of radial septa, and the presence of peculiar 

 septa which divide the body into segments. "When we make a comparative 

 survey of other Coelenterates we find that in Mseandrina separate polyps, or 

 rather oval cones, like those of Polyparium, are arranged in band-like 

 fashion on the surface of a spherical polyp-stock; the chief difference 

 between them is that the cones are more numerous in the latter. In 

 Mseandrina the tentacles do not surround every oral orifice, but are placed 

 along the margin of each band. It must be supposed that in Polyparium 

 also the tentacles migrated to the margin, and afterwards became lost ; such 



* Zcitschr. f. Wibs. Zool., xlv. (1887) pp. 669-71. t Ibid., pp. 468-90 (1 pi.). 



X See this Journtil, 1886, p. 627. 



