ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 483 



easily and appearing oval with a clear centre and deeply coloured 

 extremities ; it does not stain by Gram's method ; it is a potential 

 aerobe, grows well at all temperatures between 30° and 37° C, and 

 forms round spores at about the sixth day ; on peptone-agar it forms 

 violet colonies, and on potato a thick deep violet almost black expansion ; 

 it grows well on liquid media, but produces no pigment in the absence 

 of peptone, or in the absence of air ; it produces acetone in peptone 

 solutions, and also ethylic alcohol and volatile acids ; it liquefies gelatin ; 

 it reduces nitrates to nitrites without forming gas ; it coagulates milk, 

 the culture becoming acid, and the coagulum being slowly and completely 

 liquefied, the liquid containing casease. The author demonstrates the 

 formation of acetone, by inoculating a mixture containing peptone, 

 saccharose, sodium carbonate, and water, with a three-days-old culture, 

 and subjecting this, after incubation for a month at 30° C., to repeated 

 distillations. The amount of acetone is estimated by Jolles' method, 

 which consists in combining the acetone with bisulphite of soda and 

 titrating to find the amount of the salt that has combined. The author 

 finds that about * 78 gr. of acetone is yielded by a litre of culture. 

 He proposes to name the organism Bacillus violarius acetonicus. 



Cytology of Bacteria.* — A. Guilliermond describes his examination 

 of Bacillus radicosus, which from its large size permits a study of its 

 structure. In a less than ten-hours-old culture, after fixation in Zenker's 

 fluid and staining with iron-hagmatoxylin, almost every cell shows a large 

 deeply stained central granule, which represents the first appearance of 

 the site of transverse fission, and is formed by the union of two small 

 lateral granules apparently derived from a concentration of the cyto- 

 plasm ; this large granule, or biconcave disk, divides into two coloured 

 bands through which the division of the two cells is effected. After 10 

 to 12 hours the cytoplasm becomes vacuolated and filled with fine stained 

 granules of varying size, and later shows an alveolar structure filled 

 with fine granules resembling granules of chromatin. The spore appears 

 at one of the poles as a small deeply stained granule ; it enlarges, takes 

 an oval form, and becomes surrounded by a thick membrane which 

 prevents the penetration of stains. The spore appears to be derived in 

 part from a condensation of the granules of the cytoplasm. 



The author concludes that a true nucleus does not exist in a 

 bacterium, and that such as have been described by various authors are 

 misrepresentations, but agrees with Schaudinn that bacteria contain a 

 chromatin more or less mixed with the cytoplasm, differentiated at times 

 and constituting tbe greater part of the spore. 



Streptococcus Bombycis and Disease in Silkworms, f — S. Sarti- 

 rana and A. Paccanaro made agar and gelatin plates from emulsions of 

 the bodies of silkworms that had died from " consumption," and isolated 

 in every case, besides various bacilli, a streptococcus which in cultural 

 and morphological characters resembled the Streptococcus bombycis of 

 other authors. It occurs in the worm and in the cultures as short chains 



* Comptes Rendus, cxlii. (1906) p. 1285. 



t Centralbl. Bakt., l te Abt. Orig., xl. (1906) p. 207. 



