608 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



F. pallidum. The usual diatoms of the arctic summer plankton were not 

 present, except Ghsetoceras decipiens. Perhaps the autumn wave of arctic 

 plankton, with G. constrictum and C. Willei, moves up from the south 

 into the fjord. The horizontal distribution of organisms in the Eisf jord 

 seems to be uniform. A regular vertical distribution of organisms could 

 not be proved, which is the more remarkable as the water consists 

 almost everywhere of three layers of temperature. In the systematic 

 portion, Rhizosolenia fseroensis and R. styliformis are here recorded, 

 having only been known hitherto from more southerly waters. In all, 

 eleven species of Diatoms, two Flagellates and twenty-eight Peridiniese 

 are recorded, including three new species of Peridinieffi. The author 

 considers that the relation of the plates in Peridinium furnishes a stable 

 character for identification, which holds good in all variations and 

 conditions of growth. Breadth increases more quickly than length, and 

 the Peridinium cell becomes flatter daring growth. 



Nuclear Division in Euglena." — J. Karl writes on the nuclear 

 division of the Euglenag of the viridis type. He finds that in the 

 nucleus there is a centriolum ; and nuclear division begins with the 

 division of this body. The outer nuclear substance arranges itself in 

 filaments or chromosomes, which at first take the form of a net, but 

 soon lie parallel to one another. The chromosomes divide in half longi- 

 tudinally. Some time later the filaments form once more a nuclear 

 structure. The nuclear division of the Euglente may therefore be 

 regarded as a kind of mitosis. The paper is written in Magyar with a 

 resume in German. 



Deposits of Calciferous Alges in Lake Constance. f — E.Baumann 

 writes on the calcified strata in the Untersee, Lake Constance — namely, 

 the so-called tufaceous limestone deposits and the " Schnegglisande." 

 The former consists of a loose stratum of flint covered with a thick 

 crust of lime. On it are often clumps of Galothrix parietina, Rividaria 

 haematites, R. Biasolettiana, etc. These algae deposit lime from the 

 CaCOg extracted from the water. The tufaceous limestone is found in 

 places with a swift current, for example, in the Bay of Constance, and in 

 the Ehine up to Gottlieben, especially at Hemmishofen. Much more 

 important is the second formation, the " Schnegglisande." It consists 

 of lenticular, compressed, often hollowed, greenish lumps, strongly 

 incrusted with lime, which are piled up several metres high on the lake 

 bottom. On these occur Schizothrix laieritia, S. lyngbyaca, S.fascicidata, 

 Hyellococcus niger, Plectonema terebrans, and Gongrosira codiolifera. 

 In summer these algte bind the chalk loosely together in a zone of 

 incrustation. In winter growth is checked. As many as twenty annual 

 rings have been counted. The alga3 of the " Schnegglisande " have, 

 with their enormous deposits since post-glacial times, taken an important 

 part in the gradual filling up of the basin of the Untersee. 



* Bot. Kozlem., xiv. (1915) pp. 135-44 (figs, in text). See also Bot. Centralbl., 

 cxxxii. (1916) p. 504. 



t Verb. Schweiz. Naturf. Gesell., 96 Jahresvers. Aargau : (1914) ii. Teil. 

 pp. 207-10. See also Bot. Centralbl., exxxiv. (1917) p. 53. 



