ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 213 



Identification of Bacillus mesentericus ruber.* — Th. Gruber de- 

 scribes the cultural aspects of this orgauism, and considers that dia- 

 gnostically the growth on potato is most characteristic, consisting of a 

 broad, finely-wrinkled, soft, slimy membrane of a beautiful rose colour, 

 and having a strong odour of black currant. 



Structure of the Bacillary Endospores.f — A. Guilliermond has 

 studied the spore formation of B. railicosus, B. mz/coides, B. meg (iter ium, 

 B. Uniosas, B. alvei, B. arderosporus, and finds that at about the eighth 

 hour the cytoplasm becomes vacuolated, and shows a fine alveolar 

 stucture inclosing a number of various sized small granules situated at 

 the nodes of the network. In some cases these granules are localised at 

 the centre of each cell, giving a nuclear appearance ; these granules 

 may be regarded as of a chromatic nature. 



At the time of sporulation there is formed at one pole of the cell a 

 small deeply-stained mass, which soon becomes an oval spore, the 

 cytoplasm remaining granular, and the spores not seeming to arise from 

 a condensation of the granules. When the spore has reached a certain 

 size it is surrounded by a hyaline zone, which becomes the spore 

 membrane, the spore itself being now no longer stainable. The author 

 does not hold with other writers that the spore is a true nucleus, and 

 the hyaline zone the cytoplasm of the spore. 



In some species (B. alvei) metachromatic corpuscles were very 

 numerous, usually situated at the poles of the cells, and often reaching 

 large dimensions, so as to give a moniliform aspect to the cell ; 

 occasionally only one of these granules is present, and when situated 

 centrally has been erroneously described as a nucleus. 



Cause of the Brown-red Pigment of Hard and Soft Cheese.| — 

 Th. Gruber finds that the cause of this coloration, which arose as a 

 contamination in a North German cheese factory, is a pigment pro- 

 ducing bacterium, B. casei fusci. Its growth on ordinary gelatin and 

 agar plates was very slight, but on cheese gelatin at 16-20° C. good 

 growth was obtained, the colonies being at first grey, compact, and 

 hemispherical, later rosette-shaped and cream-coloured, becoming after 

 three weeks of a brownish-yellow. The organism is non-motile, 'and 

 does not form spores. Gelatin is slowly liquefied. 



Lactic Acid and the Dairy Industry.§ — Th. Gruber found that 

 milk carefully obtained and allowed to stand in flasks at room tempera- 

 ture for several days become clotted. Stained preparations of this clot 

 show true lactic acid bacteria, although in the freshly-drawn milk there 

 were none obtainable by cultivation. By culture methods the author 

 finds that lactic acid bacteria can be demonstrated in straw and grass, but 

 not in cow-dung. 



He isolated fourteen strains of lactic-acid-forming organisms, and 

 has classed them into three divisions : those of the first group split up 



* Centralbl. Bakt., 2te Abt. xvii. (1906) p. 644. 



t Comptes Rendus Soc. Biol, de Paris, Ixii. (1907) p. 78. 



X Centralbl. Bakt., 2te Abt., xvii. (1907) p. 761. 



§ Tom. cit., p. 755. 



