ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 81 



A. Chromatophore single. 



I. Chromatophore divides by longitudinal fission. 



(a) Without translocation (Umlagerung), Rhoicosphenia, 



Cymbella, Encyonema, Gomphonema, Epithemia. 

 (o) With translocation. 



(a) With previous translocation, Amphipleura. 

 (/?) With subsequent translocation, Cymatopleura, 

 Surirella, Campylodiscus. 



B. Chromatophores two. 



I. Chromatophores divide by longitudinal fission, Nitzschia. 

 II. Chromatophores divide by transverse septation. 



(a) With subsequent translocation, Synedra, Eunotia. 



(b) With previous and subsequent translocation, Fragilaria, 



Pleuroslgma, Navicula, Finnularia. 



Colourless Diatoms.* — The cultivation by G. Karsten of Nitzschia 

 jmlea in favourable nutrient media — glycerin, glycocoll, and grape- 

 sugar — brought out the peculiarity of the appearance of a fatty shimmer 

 (Speckglanz) throughout the cell-contents, larger or smaller fat-like 

 drops being dispersed among them. The size of the chromatophores 

 gradually decreased, especially when the culture was exposed to strong 

 illumination ; and they were finally reduced to a minute dot-like residue 

 but the diatoms still retained their power of motion under the sapro- 

 phytic conditions, and the capacity for propagation was increased. On 

 the other hand, all attempts to induce the production of chromatophores 

 or leucoplasts in the colourless Nitzschia putrida failed. 



Stauronella, a New Genus of Diatoms.f — Out of Stauroneis constricta 

 Ehr., C. Msreschkowsky proposes to establish a new genus Stauronella, 

 with the following characters: — Valve narrow, linear, or attenuated 

 towards the ends, usually constricted in the middle ; extremities truncate 

 or ro mded, rarely cuueate; raphe straight, symmetrical; central nodule 

 elongated transversely in a stauros ; girdle-face constricted, zone com- 

 plex; enduchronie composed of two plates disposed transversely along 

 one of the connecting zones, each plate with a conspicuous pyrenoid. 



Okedenia.J — C. Mereschkowsky proposes the re-establishment of this 

 MS. genus of diatoms of Eulenstein's, to include Navicula scopulorum 

 Breb., Amphipleura inflexa Breb., and two new species. The following 

 is the diagnosis of the genus : — Valve elongated, very narrow, linear, 

 often inflated at the middle and at the extremities, straight and sym- 

 metrical, or arcuate and asymmetrical, terminal nodules usually distant 

 from the margin ; striae fine ; connecting zone complex ; endochrome 

 composed of numerous chromatophores usually of the shape of the letter 

 H, sometimes rounded, disposed in pairs along the connecting zone, 

 rarely along the valves, with a central pyrenoid usually common to each 

 pair. 



• Flora, lxxxix. (1901) Ergz.-Heft, pp. 404-33(1 pi.). Cf. this Journal, 1901, 

 p. 306. 



+ Ann. Nat. Hist., viii. (1901) pp. 424-34 (1 pi. and 3 figs.). 

 X Tom. cit., pp. 415-23 (1 pi. and 2 figs). 



Feb. 19th, 1902 a 



