152 BUTYRIC ACID FERMENTATION 



from remote ages without any special knowledge of the more delicate processes 

 involved. According as the moisture necessary for this fermentation (or for the 

 development of the fission fungus effecting the same) is imparted to the rippled 

 stalks by means of dew, sprinkling them with water, or by immersion, the 

 process is known as dew -retting, water-retting, or, finally, mixed retting. 



With reference to the bacterial species taking an active part in this process, 

 VAN TIEGHEM (VI.) in 1879 expressed the opinion that they should be assigned 

 to his Bacillus amylobacter, which he, as already mentioned, also regarded as the 

 cause of cellulose fermentation. The inaccuracy of this view is evident, since, 

 if the retting (Fr. rouissage, Ger. rosten) of the flax were mainly a process of 

 cellulose fermentation, there would not be much of the fibre (which chiefly con- 

 sists of cellulose) left. It was V. Fribes who working under the directions 

 of S. WINOGRADSKY (I.) in 1895 clearly proved the true state of the case and 

 made known the active agent of this pectin fermentation. This organism is a 

 fairly large-celled species, occurring in the form of rods, which, when young, 

 have a length of 10-15/1 with a breadth of 0.8 p, but subsequently become 

 broader )i /*), and swell up to a thickness of 2 p. at the one end (tadpole shape), 

 where a long endospore (1.2 x 1.8 p.) is developed. This (anaerobic) bacillus will 

 not grow on gelatin, but when supplied with nitrogenous food in the form of 

 peptone will ferment glucose, saccharose, lactose, and starch, leaving these, how- 

 ever, untouched when the peptone is replaced by ammonia salts. On the other 

 hand, even in this latter case, any pectin bodies that may be present, i.e. pectin 

 and pectic acid, are fermented, and that, too, even more readily than the carbo- 

 hydrates already mentioned. The organism, however, has no action on cellulose 

 and gum-arabic. When clean portions of plants, previously washed, first with 

 acidified, and then with faintly alkaline, water (free from bacteria), are exposed 

 to the action of pure cultures of this bacillus, they quickly lose the greater 

 portion of their pectin content, the loss of weight they suffer being almost 

 exclusively due to this cause. As reported by E. PFUHL (II.), a patent has 

 been obtained in the United States by Allison and Pennington for the method 

 tested by them, whereby the retting of flax can be effected in a few days in any 

 class of water by the addition of salts promoting the growth of the desired 

 ferment. Perhaps an inoculation by water from a locality such as the river 

 Lys, a tributary of the Scheldt where flax-retting is extensively carried on is 

 also to be made. 



120. The Rancidity of Fats, particularly Butter, 



will be briefly dealt with here parenthetically, as there is no other appropriate place 

 for it. The characteristic indication of this well-known phenomenon is an increase 

 in the percentage of free acids (chiefly the volatile acids, butyric, caproic, &c.). 

 This may be attributed to four different causes : (i) The activity of lactic acid 

 bacteria converting the residual lactose in the butter into lactic acid, which latter 

 is then transformed into butyric acid by Granulobacter lactobutyricum ; (2) the 

 decomposition of albuminoids (casein) by bacteria capable of forming butyric 

 acid therefrom ; (3 and 4) the dissociation of the fats into glycerin and free 

 fatty acids, either by bacterial agency on the one hand, or by the action of light 

 and air on the other. The preponderance of one or other of these causes 

 depends on the attendant circumstances. 



E. DUCLAUX VI.) rendered valuable service in demonstrating the influence 

 of air on the fatty matter of butter and cheese, and by showing that this 

 influence is twofold, viz., it first, by saponification, breaks the matter up into 

 glycarin and fatty acids, and then converts the latter (especially oleic acid) into 

 oxy compounds. In the dark, and in presence of a copious supply of air, saponi- 



