736 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Cell-wall Structure and Ring-formation in (Edogonium.* — C. van 

 Wisst'iilingh gives a detailed account of the ring and the cell-wall of 

 (Edogonium. He summarises previous work on the subject, and de- 

 scribes his own methods of investigation. He finds that the cell-wall 

 consists of two layers which are chemically quite distinct, the inner 

 lamellate and rich in cellulose, the outer containing little cellulose and 

 much special material. The outer layer also consists of a cylindrical 

 portion and of one or several ring-shaped portions, to which in the apical 

 cell is added a cup-shaped portion. When a cell is about to divide, a 

 ring (or, in certain cases, a sort of apical cup with a thickened edge) is 

 formed at the upper end, and is of similar chemical constitution to that 

 of the outer layer of the cell-wall, with a preponderance of cellulose on 

 the inner side. The origin and growth of the ring can only be explained 

 by intussusception. Upon the splitting of the ring (or of the thickened 

 edge of the above-mentioned apical cup) different results follow, accord- 

 ing to whether the cellulose part alone splits, or the outer layer also 

 splits ; upon this depends the presence or absence of the persistent outer 

 ring-fragments. The young transverse wall is a loose plate, free from 

 cellulose, and grows centrifugally. In a supplement the author points 

 out wherein his observations differ from those of Kraskovits, Hirn, and 

 others. 



Observations on the Germination of some Phaeophyceae. — C. 

 Sauvageau | publishes some further observations on the germination of 

 Cladostephus verticillatus. Having previously described the germination 

 of the zoospores of the unilocular sporangia, he describes that of the 

 zoospores of the plurilocular sporangia. These are of one sort only. 

 They are very active, and settle down in a few hours, round themselves 

 off, and become clothed with a membrane. After ten days, during 

 which they lose their red spot and become deep brown owing to multi- 

 plication of the single chromatophore, they divide and branch and forcn 

 a little round flat disk. From this the erect filaments subsequently 

 arise. The germination is indirect. These zoospores then are asexual 

 like those of the unilocular sporangia, and the product of their germina- 

 tion is the same. 



He describes J further results of his cultivations of the zoospores of 

 Aglaozonia melanoidea. These he has carried out for the third time by 

 means of cellular cultures. Dehiscence of the sporangia occurred in 

 mid-January. Among the thousands of germinations obtained, about 

 1 p.c. were Aglaozonia (that is, asexual plants), and the rest Cutler ia 

 (sexual plants). 



He gives § the results of his cultivation of Cvtlcria adspersa, which 

 show that, contrary to the opinion of Reinke, Falkenberg, and Janc- 

 zewski (that in the Mediterranean the unfecundated oospheres do not 

 germinate), the oospheres of Cutleria adspersa do germinate by partheno- 

 genesis in the Mediterranean (at least at Banyuls) as well as they do in 

 the Atlantic. A priori, Zanardinia and Cutler ia multifida ought to 

 present the same phenomenon. His experiments also show that his 



* Beih. Bot. Centralbl., lte Abt., xxiii. (1908) pp. 157-90 (4 pis.). 



t C.R. Soc. Biol. Paris, lxiv. (1908) pp. 695-7. 



J Tom. cit., pp. 697-8. § Tom. cit., pp. 698-700. 



