44 SUMMARY OF CURRENT RESEARCHES RELATING TO 



and tlie ciliated bands ; in egg-embryos the glandular streaks develope 

 before the ciliated bands make their appearance ; in the same embryos 

 the streaks make their appearance on mesenteries that are not connected 

 in any way apparently with the ectoderm ; and in hud-embryos the. 

 ciliated bands appear before the glandular streaks. Therefore it seems 

 to the author that the ciliated bands must be regarded as being onto- 

 genetically distinct from the glandular streaks. But although he is 

 prepared to call the ciliated bands ectodermal in all cases, the glandular 

 streaks seem to be endodermal in some mesenteries and ectodermal in 

 others. But since every kind of cell — glandular, muscular, sensory, 

 ganglionic, and even nematoblastic — which occurs in the ectoderm, may 

 also occur in the endoderm, it seems to the author that in Ccelentera 

 the two layers are hardly as yet differentiated from one another. 



Anemones from Jamaica.* — Mr. J. E. Duerden publishes a second 

 instalment of his work on this subject, containing descriptions of various 

 members of the order Stichodactylinaa, and of three new species of 

 Parazoanthus. He divides the order StichodactylinsB into two new sub- 

 orders : — (1) Heterodactylinse, in which the tentacles are of two forms; 

 and (2) Homodactylinaa, in which they are all of one kind. In regard 

 to the genus Parazoanthus, the author notes that pigment-granules and 

 zooxanthella? are present in inverse ratio to one another, the granules 

 of certain species a]>pearing to replace the zooxanthellseof other species. 

 He finds that this is also the case in other families of Actiniaria, and 

 suggests that the pigment-granules may perform the same function as 

 the zooxanthellse, and may be regarded as free chromoplasts. 



Protozoa. 



Sexual Zygosis in Protozoa.f — Prof. E. Bay Lankester points out 

 that the microgametes in the Coccidiidad and Haemamoebidse are similar 

 to the spermatozoa of Metazoa both in appearance and in mode of develop- 

 ment. He emphasises this point by a detailed comparison of the pro- 

 cess by which the microgametes arise in those Protozoa, and the method 

 of formation of spermatozoa in the earthworm, which shows how close 

 the resemblance is. But it is remarkable that the zygote of the malarial 

 parasite after fertilisation gives rise to blasts or filiform young, which in 

 form and mode of development are identical with microgametes. In 

 other organisms the fertilised egg-cell produces as fission-products cells 

 which are similar to female cells (oomorphous or gynsecomorplwus cells), 

 but in the HosmamoebidaB the fertilised zygote produces andromorphous 

 or spermatomorphous cells. As these cells are capable of carrying on 

 the life of the species without conjugation, the author believes that we 

 have here parthenogenesis by means of male elements (androcratic par- 

 thenogenesis), and that the existence of these spermatomorphous blasts 

 is "a distinct proof that the spermatozoon is, so far as its essential 

 nature is concerned, capable of acting the part of the solely sufficient 

 germ in a parthenogenetic reproduction or multiplication." 



Karyokinesis in Vampyrella.} — Prof. P. A. Dangeard describes 

 the karyokinesis of V. vorax. The chromosomes seem to arise in the 



* Trans. Roy. Soc. Dublin, vii. (1900) pp. 133-208 (6 pis.). 

 t Quart. Journ. Micr. Sci., xliii. (11)00) pp. 5S1-8 (13 figs.). 

 J Le Botanisto (Dangeard), vii. (1900) pp. 131-58 (1 pi.). 



