ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 103 



younger cells the chromatophores occur in the form of a band or 

 thread ; in the older cells in that of granules ; in Oocystis they take 

 the form of small parietal disks. The so-called " nucleus " described 

 by Eabenhorst is really only a vacuole. The granules in the larger 

 cells have a diameter of • 5-2 ■ /x, and form an open or closed sac 

 lying at some distance from the cell-wall, and inclosing colourless 

 cell-contents ; they are themselves of a beautiful blue-green colour. 



Gongrosira.* — J. Schaarschmidt has examined the structure and 

 development of Gongrosira de Baryana, and finds that its chlorophore 

 forms a large layer lining the cell ; and that when division takes place, 

 this layer splits in a direction corresponding to that of the septum. 

 The cell-wall consists of two layers, an outer thicker one, which 

 swells up greatly and may become converted into mucilage, and 

 an inner much thinner one which shows a bluish refraction. The 

 resting spores are of two kinds : one green, and multiplying by 

 division, the other with reddish very granular contents, rich in starch, 

 and a greatly thickened mucilaginous membrane. 



With regard to the systematic position of Gongrosira, the author 

 points out that the discovery in G. de Baryana of plates of chloro- 

 phyll destroys the distinction sought to be drawn by Borzi between 

 the Chroolepidacese and the Ulotrichaceae. The suggested identity 

 with TrentepoMia cannot be affirmed until more is known about the 

 germination of the zoospores. 



Diatoms from Lago Trajano.f — M. Lanzi has examined the 

 diatoms from Lago Trajano (the ancient Trajan's haven), now no 

 longer in communication with the sea, and the adjacent Stagno di 

 Maccarese, which has an outlet to the sea. He finds 120 species and 

 varieties, partly brackish, partly fresh-water, and in addition 8 marine 

 species. The limitation of the power of motion possessed by the 

 frustules of Bacillaria (Nitzschia) paradoxa he considers to be due to 

 the elastic sheath of mucilage in which the whole colony is imbedded. 

 He confirms the statement of Hamilton Smith, Grunow, and Van 

 Heurck, that the shells of Craticula Ehrenhergii (Surirella craticula) 

 correspond to a single easily separable part of the shell of Navicula. 



Schmidt's 'Atlas der Diatomaceen-Kunde.' — C. H. Kain has 

 reproduced this work in blue photo-zincography, reduced from the 

 original size of 12 in. X 9 in. to 6 in. x 4^ in. It is impossible to 

 say that the reproduction is wholly satisfactory so that it might be 

 used as a substitute for the original, but no doubt many microscopists 

 will find it useful both on account of the high price of the original 

 and its scarceness. 



liichenes. 

 _ Algo-Lichen Hypothesis.^— The Eev. J. M. Crombie deals with 

 this hypothesis as enunciated by Schwendener, Bornet, and others. 



* Magyar Noveny t. Lapok, vii, (1883) pp. 129-38 (1 pi. ). See Bot. Centralbl., 

 xix. (1884) p. 321. 



t Atti Soc. Crittogara. Ital., iii. (1884). See Bot. Centralbl., xix. (1884) p. 161. 

 X Jotirn. Linn, Soc. Lend. (Bot.) xxi. (1884) pp. 259-83 (2 pis.). 



