THE GENUS GRANULOBACTER 145 



addition to producing butyric acid, and forms one of the many connecting links 

 between the butyric acid bacteria (in the restricted sense of the term) and the 

 so-called potato bacilli. No sharply de6ned limit can be drawn between these 

 two groups. In the same category must also be included one of the two species 

 of bacteria which were isolated in 1894 by W. KEDROWSKI (I.) from a butyric 

 fermentation produced by a method approximating to that of Pelouze. In still 

 closer relation to the potato bacilli are a few anaerobic species isolated by 

 C. FLUGGE (II.) from boiled milk, as also the Bacillus liodermos, frequently 

 observed by LOEFFLER (III.) in imperfectly sterilised milk. 



116. The Genus Granulobaeter. 



As the reader will be aware, organic chemistry distinguishes between two 

 kinds of butyric acid, only one of which, viz., the propyl carboxylic acid, having 

 the subjoined formula 



CH 3 -CH 2 - CH 2 COOH, 



is, in the present state of science, known to result from butyric acid fermenta- 

 tion, on which account it is also called fermentation butyric acid. On the other 

 hand, the isomeric acid, which, in accordance with its constitution 



CH, H CH 3 



.COOH 



CH.( 



CH 3 COOH CH 3 



is also styled dimethylacetic acid or isopropyl formic acid, has not hitherto been 

 obtained by the aid of fermentation. However, not only the first-named acid, 

 but also the corresponding alcohol, viz., normal butyl alcohol, 

 CH 3 CH 2 CH 2 CH 2 OH, 



can be produced by the activity of fission fungi ; so that we may also speak of a 

 group of the bacteria of butylic fermentation. In this connection we are 

 indebted to M. W. BEYERINCK (XII.) for some thoroughgoing researches, which 

 have not only brought new facts to light, but also led to a more definite charac- 

 terisation and limitation of a number of species of butyric acid bacteria. This 

 observer has given to the bacteria of butylic fermentation the common generic 

 name of Granulobaeter, since they all possess the faculty of storing up granulose 

 in the interior of their cells, owing to which they are stained blue by iodine. 

 The characteristics of this genus are given by Beyerinck as follows : " Strictly 

 or temporarily anaerobic fermentative bacteria, which in a condition of complete 

 anaerobiosis become partly or entirely filled with granulose, and then assume 

 the clostridium form. In presence of traces of oxygen, short motile rods are 

 quickly produced, which are stained yellow by iodine. Endospores make their 

 appearance in the c'ostridia. They are able to remain uninjured for a few 

 seconds or minutes at a temperature of 95-ioo 0. Among the products of the 

 fermentations set up by individual species of this genus are : carbon dioxide 

 always and hydrogen generally, but methane is never found." 



Granulobaeter butylicum is the species producing butyl alcohol. It is pre- 

 sumably identical with Gruber's Bacillus amylobacler /., and is frequently met 

 with in the flour of cereals. It is anaerobic, and produces from maltose normal 

 butyl alcohol, hydrogen, and caibon dioxide, but no butyric acid ; diastase is 

 formed concurrently, but not glucase. A spontaneous butyl-alcoholic fermenta- 

 tion can be set up by gradually adding to 100 c.c. of boiling water as much 

 coarsely ground, unsifted, fresh barley-meal (from Hordeum di&tichum nudum) 



