ZOOLOGY AND BOTANY, MICROSCOPY, ETC. /9 



Structure of Bacteria.* — F. Schaudinn describes his observations on 

 the structure of a new bacillus, the B. Batschli, which he isolated from 

 the midgut of the large kitchen beetle (Periplaneta orientalis). His 

 observations were chiefly directed to the structure of the organism, its 

 method of spore-formation, and of spore-germination. The bacillus 

 occurs as a long cylindrical rod with rounded ends, about 50 to 60 /x in 

 length (maximum noted 80 /*). The cell is enclosed in a somewhat 

 dense membrane, which does not give a cellulose reaction. The finely 

 granular cell protoplasm contains numerous coarser granules in its 

 substance which form the nodal points of a distinct network, the whole 

 giving an appearance of an alveolar system. Morphological differentia- 

 tion of a nucleus was not observed, but the author considers that the 

 nodal points of the network, scattered throughout the cell-protoplasm, 

 correspond to the aggregation which in the higher organisms receives 

 the name of nucleus. The vegetative reproduction of the organism is 

 preceded by the collection of several of these coarse granules to the 

 opposite poles of a bacillus ; these shortly become more highly refractile 

 and stain intensely. This stage is followed by the appearance of a 

 septum at right angles to the long axis of the bacillus, which, com- 

 mencing in the centre, soon spreads to the enclosing membrane and 

 separates into two lamellae ; finally division takes place at the site of this 

 septum. Spore-formation is characteristic, in that two spores are formed 

 in each bacillus ; the preliminary stages of aggregation of granules to 

 the poles and the appearance of a central septum occur as a vegetative 

 reproduction. At this point, however, the septum becomes resolved and 

 finally disappears, leaving no trace of its presence behind. The proto- 

 plasm round the polar granules becomes condensed and forms the spore- 

 capsule, and the perfect spores are now oval or ellipsoid in shape. The 

 author is of opinion that the appearance and subsequent disappearance 

 of the septum is an indication of a process analogous to the conjugation 

 of the reproductive cells of higher organisms. Spore-formation only 

 takes place in beetles which are overfed, but may be produced artificially 

 by inoculating in a mixture of intestinal secretion and saliva. In the 

 actual process of germination, the young bacillus grows out through one 

 of the poles of the ellipsoid, elongates, and takes on the characteristic 

 form of the bacillus, almost immediately showing the distinctive alveolar 

 arrangement of the protoplasm. 



Psychrophilic Bacteria.f — S. Schmidt-Nielsen has studied numerous 

 bacteria with respect to their capacity for growth at 0° C. He finds 

 that the B. aquatilis fluorescens non-liquefaciens grows well in 10 days ; 

 the B. granulosum in 40 days ; B. paracoli gaso-formans feebly in 

 40 days ; B. radiatum feebly in 10 days, but more vigorously in 40 days ; 

 and the B. tardi fluorescens feebly in 40 days. From earth and from 

 vegetables the author isolated 15 other varieties (which on account of an 

 accident he was unable to identify) which possess a similar capacity. So 

 also two unnamed saccharomyces, and a pink torula isolated from the 

 shell of a deep-water shrimp, are capable of multiplying at 0° C. Three 



* Centralbl. Bakt., l t8 Abt. (Ref.). xxxii. (1902) pp. 139-40. See also Archiv. f. 

 Protistenkuude, 1. (1902) pp. 306-43. 



t Centralbl. Bakt., 2" Abt., ix. (1902) pp. 145-7. 



