ZOOLOGY AND BOTANY, MICliOSCOPY, ETC. G7 



from its characters and those of others described hy Klebs, proposes 

 some modification of the characters of the genus. Each cell possesses 

 a nucleus, a disk-shaped chromatophore, and one or more pyrenoids. 

 The megazoospores have in some species 2, in others 4 cilia, and 

 germinate readily. The microzoospores have also either 2 or 4 cilia, 

 corresponding to "the number in the megasporesof the same species. The 

 microspores do not germinate directly, but pass into a resting-stage. or 

 conjugate in pairs, producing stellate zygotes. The resting palmella- 

 cells may either germinate directly or produce microzoospores. 



Plankton Algae. — In addition to a number of new species, E. 

 Lemmermann * adds the following new genera to the list of plankton 

 algae. 



Centratr actus g. n. Cells free-swimming, furnished with a long 

 hollow spine distinctly thickened at the base, with several chlorophores 

 which are often broken up into a network ; no pyrenoid ; propagation 

 by transverse division. Founded on Sclircederia belonophora Schmidle. 



Marssoniella g. n. Cells mostly associated in a tufted radiating colony, 

 pear-shaped, connected by the blunt ends, with homogeneous blue-green 

 contents, and a more strongly coloured central body ; propagation by 

 division. 



Eudorinella g.n. Cells associated in spherical colonies of 8, biciliate, 

 enclosed in a common broad gelatinous envelope ; the peripheral cells 

 lying in two different planes, forming regular cubes ; chlorophore 

 parietal, with a pyrenoid (?) ; an eye-spot (?) ; propagation unknown. 

 Founded on Eudorina Wallichii Turn. 



Crucigenietta g.n. Cells associated in definite colonies; with a 

 parietal chlorophore, but no pyrenoid ; propagation by longitudinal 

 division. 



A synopsis is given of the 5 species of Lagerheimia. 



Prof. G. B. De Toni and Sig\ A. Forti f furnish a list, with descrip- 

 tions of 45 genera and 85 species of plankton-algae (including Peri- 

 dinieae) found in Lake Vetter, Sweden. 



Among Plankton diatoms H. IT. Gran J proposes a new genus 

 Bacterosira, founded on Lauderia fragilis, and another new genus 

 Cuscinosira, founded on Coscinodiscus polychordus. 



Development of Pandorina morum.§ — According to P. A. Dangcard, 

 each zoospore is, in this alga, identical in structure with a Chlamydomonas 

 with bell-shaped chromatophore. It possesses a nuclear membrane, a 

 nucleole, and nucleoplasm. Each zoospore is invested with a membrane 

 of its own, and secretes in addition a gelatinous substance, which goes 

 to the formation of the common envelope of the colony. The division 

 of the nucleus is karyokinetic, and exactly follows the same course as 

 in the Cldamydomonadineae. In (he formation of a new colony, which 

 generally consists of 16 individuals (though there may be 8 or 32), thore 

 is not simply an invagination of the cells, each one must undergo a 



* Bcr. Deutsch. Bot. Ges., xviii. (1900) pp. 272-5, 306-10. Cf. this Journal, 

 1900, p. 612. f Atti r. 1st. Veneto di Sci., lix. (1900) pp. 537-61, 780-829. 



I Nyt Ma-. Naturvidensk., xxxiii. (1900) pp. 103-28 (1 pi.). See Hedwigia, 

 xxxix. ( 1900) Beibl., p. 203. 



§ Le Botaniate (Dangeard), vii. (1900) pp. 192-208 (1 pi.). Cf. this Journal, 

 1900, p. 229. 



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