PRODUCTS OF VITAL ACTIVITY. 139 



attached to the upright tube is then filled with carbon dioxide and a 

 culture of the butyric-acid bacillus is introduced into the funnel. 

 By turning the stopcock in the upright tube a little of the culture is 

 admitted to the flask without admitting any air. Fermentation com- 

 mences very soon, as is seen by the bubbles of gas given off. The 

 liquid loses its transparency and the lactic acid is gradually con- 

 sumed, butyrate of lime taking the place of the lactate. 



Aerobic bacilli capable of producing butyric acid in culture solu- 

 tions containing grape sugar or milk sugar have also been described 

 by Liborius and by Hueppe. 



Fitz has shown that in culture solutions containing glycerin the 

 Bacillus pyocyaneus produces butyric acid in addition to ethyl alcohol 

 and succinic acid. Bacillus Fitzianus also produces some butyric acid 

 in solutions containing glycerin, although the principal product of the 

 fermentation caused by this microorganism is, according to Fitz, 

 ethyl alcohol, twenty-nine grammes of which may be obtained from 

 one hundred grammes of glycerin. 



Botkin (1892) has described a "Bacillus butyricus" (No. 46G) 

 which he has not been able to identify positively with the butyric- 

 acid ferment described by Prazmowski. It is a widely distributed 

 anaerobic bacillus, which he was able to obtain from milk or water 

 containing it by placing it in the steam sterilizer for half an hour. 

 The spores resisted this temperature and subsequently grew in anae- 

 robic cultures, in a suitable medium, while all other bacteria and 

 spores present were destroyed. 



The writer has described a bacillus which causes active acid 

 fermentation in culture solutions containing glycerin. The acid 

 formed is volatile and is probably propionic acid see Bacillus acidi- 

 formans. 



The Caucasian milk ferment Bacillus Kaukasicus produces 

 a variety of products in the fermented milk which is a favorite 

 drink among the Caucasians. The principal ones are ethyl alcohol, 

 lactic acid, and carbon dioxide, but in addition to these small quanti- 

 ties of succinic, butyric, and acetic acids are formed. The inhabi- 

 tants of the Caucasian mountains prepare this fermented drink in a 

 very simple manner from the milk of cows or goats, to which they 

 add the dried ferment collected from a receptacle in which the fermen- 

 tation had previously taken place. Flugge gives the following di- 

 rections for the preparation of this drink : 



" Two methods may be employed. In the first the dry brown kefir-kor- 

 ner of commerce are allowed to lie in water for five to six hours until they 

 swell; they are then carefully washed and placed in fresh milk, which 

 should be changed once or twice a day until the korner become pure white 

 in color and when placed in fresh milk quickly mount to the surface in 

 twenty to thirty minutes. One litre of milk is then poured into a flask and a 

 full tablespoonful of the prepared korner added to it. It is allowed to stand 



