§ IX.] Bacillus Amylobacter. loi 



cells make their appearance irregularly mixed up together and 

 connected with one another, as Fig. 13 shows. 



In its mode of life, Bacillus Amylobacter is a type of Pasteur's 

 anaerobia (page 54), though the possibility of its vegetating 

 in the presence of oxygen is not excluded. Living in this 

 manner it is first of all the chief promoter of butyric acid- 

 fermentations of sugars, that is, of fermentations in which 

 butyric acid is the primary product and is accompanied by other 

 products which vary greatly according to the special material, 

 as is shown by the researches of Fitz. It may also be assumed 

 that it is this species which causes butyric acid-fermentation 

 in lactates, though an objection brought by Fitz against this 

 view has not yet been quite removed. In this special cha- 

 racter of the ferment of butyric acid B. Amylobacter plays 

 an important part in human economy, whether as the cause of 

 fermentation in acid articles of vegetable food which in this case 

 rapidly rot, or of the butyric acid-fermentation which is essential 

 to the ripening of cheese. 



Bacillus Amylobacter is also a specially active agent, as van 

 Tieghem has shown, in the decomposition of decaying parts of 

 plants by destroying the cellulose of the cell-membrane. It 

 does not attack all cell-membranes, not for example suberised 

 membranes, those of bast-fibres, of submerged water-plants, of 

 Mosses and many Fungi ; on the other hand, the membranes of 

 fleshy and juicy tissues, as in leaves, herbaceous stems, cortex, 

 tubers of land-plants, and softer kinds of wood, are especially 

 liable to its attacks. In all these cases it first of all decomposes 

 the cellulose into dextrin and glucose by means of a diastatic 

 enzyme which it disengages, and these then undergo the 

 butyric acid-fermentation. Most starch - grains escape its 

 attacks, but paste and soluble starch are very liable to them. 

 Hence the maceration and destruction of parts of plants that 

 are kept wet are to a great extent the work of this Bacillus, 

 aUke in cases which involve the economical processes of mankind, 

 such as the maceration and rotting in water of hemp, flax, and 



