90 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
B. viscosus odoraceus is 1 * 25-6 p long and 0 * 7 broad ; it often forms 
filaments, especially at temperatures over 26°. It is easily stainable, but 
not by Gram. On gelatin, which is liquefied, chrome yellow colonies 
are formed. Along the track in thrust cultures the growth, which is 
colourless, resembles a series of closely packed granules, imparting a very 
characteristic appearance. On agar, at ordinary temperature, the surface 
film is of a chrome-yellow colour. On potato there forms a granular 
coherent mass of a yellow hue, but having a dash of green in it. At in- 
cubation temperature there is no pigment formed. Both pigments are 
soluble in water, but not in ether or alcohol. They are decolorized by 
nitric acid, and restored by alkalies. 
Acetifying Bacteria.* — The recent investigations of M. E. C. Hansen 
on acetifying bacteria were made with Bact . aceti , Bad. pasteurianum , and 
Bad. Kutzingianum. Though several kinds of nutritive media were 
used, the most favourable was found to be double beer, a high fermentation 
product relatively rich in extractives and poor in alcohol. Acetifying 
bacteria are classified by the author as follows : — A. Species forming 
easily separable membranes, in which the gelatinous formation can 
only be observed by means of special preparation. (1) The jelly is not 
coloured by iodine solution nor by iodopotassic iodide. B. aceti (TJlvina 
aceti , Mycoderma aceti), when cultivated in double beer, forms at 34° a 
smooth glairy membrane ; the cells are, for the most part, hour-glass- 
shaped rodlets, in chains. Sometimes there are swollen forms and 
filaments ; on other media there is less tendency to form chains. (2) 
The jelly is coloured blue by solution of iodine and by iodopotassic 
iodide. Bact. pasteurianum ( Mycoderma pasteurianum ) forms at 34° in 
double beer a dry membrane, which soon gets wrinkled and puckered. 
The cells are longer and thicker than those of B. aceti ; long chains are 
formed. Bact. Kutzingianum forms in double beer at 34°, a membrane 
much resembling that of B. pasteurianum, but rises more above the level 
of the fluid, and crawls up the side of the cultivation vessel. The rod- 
lets are small, usually single or in pairs, rarely forming chains. 
B. Species forming a membrane, in which the jelly becomes cartilaginous 
or coriaceous. Bact. xylinum. 
Several illustrations are given to show certain morphological changes 
which occur to B. aceti and B. pasteurianum. These are the filamentous 
and swollen forms ; and with regard to the latter the author finds that 
these apparently abnormal forms are regularly produced, and actually 
indicate that energetic increase is taking place. The morphological and 
physiological remarks are preceded by a historical introduction. 
Bacterium radicicola.f — From an examination of the nodules on the 
rootlets of lupins Dr. E. Klein finds that two distinct species of Bacteria 
are present in these “ tubercles.” One is a liquefying bacillus which 
imparts to gelatin and agar a greenish fluorescent appearance ; while 
the second species, which is a small oval motionless bacillus, forms only 
small punctiform colonies and only softens the medium after 12-14 days. 
The former bacterium tends to spread over the medium like Proteus 
* Ann. de Micrographie, vi. (1894) pp. 385-95, 441-70 [(14 figs.), Cf. this 
Journal, 1894, p. 384. 
t Journ. of Pathol, and Bacteriol., ii. (1893), pp. 205-13 (8 figs.). 
