132 PRODUCTS OF VITAL ACTIVITY. 



Botkin has recently (1892) described a "Bacillus butyricus" 

 (No. 466) which he has not been able to identify positively with the 

 butyric-acid ferment described by Prazmowski (No. 404). 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 anaerobic cultures, in a suitable medium, while all other bac- 

 teria 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 (No. 93). 



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. Fliigge gives the following di- 

 rections for the preparation of this drink : 



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

 ner of commerce are allowed to lie in water for five to six bours 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 

 open for five to eight hours ; the flask is then closed and kept at 18 C. It 

 should be shaken every two hours. At the end of twenty- four hours the 

 milk is poured through a fine sieve into another flask, which must not be 

 more than four-fifths full. This is corked and allowed to stand, being 

 shaken from time to time. At the end of twenty-four hours a drink is ob- 

 tained which contains but little COa or alcohol. Usually it is not drunk 

 until the second day, when, upon standing, two layers are formed, the 

 lower milky, translucent, and the upper containing fine flakes of casein. 

 When shaken it has a cream- like consistence. On the third day it again 

 becomes thin and very acid. 



" The second method is used when one has a good kefir of two or three 

 days to start with. Three or four parts of fresh cow's milk are added to one 

 part of this and poured into flasks which are allowed to stand for forty- 

 eight hours with occasional shaking. When the drink is ready for use a 

 portion (one- fifth to one- third) is left in the flask as ferment for a fresh 

 quantity of milk. The temperature should be maintained at about 18 C. ; 

 but at the commencement a higher temperature is desirable. The korner 

 should be carefully cleaned from time to time and broken up to the size of 

 peas. The cleaned korner may be dried upon blotting paper in the sun or 

 in the vicinity of a stove : when dried in the air they retain their power to 

 germinate for a long time." 



Fermentation of urea. The alkaline fermentation of urine is 



