PRODUCTS OF VITAL ACTIVITY. 137 



effected by various microorganisms, but chiefly by the Micrococcus 

 ureae, the ferment action of which has been carefully studied by Pas- 

 teur, Duclaux, and others. The change which occurs under the 

 action of the living ferment was determined by the chemist Dumas 

 as long ago as 1830, but it remained for Pasteur to show that this 

 change depends upon the presence and vital activity of a living 

 microorganism. 



The transformation of urea into carbonate of ammonia is shown 

 by the following formula : COH 4 ST + 2H 2 O = CO 2 + 2NH 9 + 

 H,0 - (NHJ.CO,. 



According to Van Tiegheni, Micrococcus ureae continues to grow 

 in a liquid containing as much as thirteen per cent of carbonate of 

 ammonia. It may be cultivated in an artificial solution of urea, with 

 the addition of some phosphates, as well as in urine. 



The Bacillus ureae of Miquel has also the power of producing the 

 alkaline fermentation of urine, but it does not thrive in so strong a 

 solution of carbonate of ammonia. 



A different micrococcus Micrococcus ureae liquefaciens nas also 

 been studied in Fliigge's laboratory which possesses the same power. 

 According to Musculus, a soluble ferment may be isolated from urine 

 which has undergone alkaline fermentation, which changes urea into 

 carbonate of ammonia. He obtained it from urine containing con- 

 siderable mucus, in a case of catarrh of the bladder. But Leube has 

 shown that cultures of Micrococcus ureas from which the micrococ- 

 cus was removed by filtration through clay do not induce alkaline 

 fermentation. The soluble ferment obtained by Musculus must 

 therefore be from some other source. 



Miquel has given special attention to the study of bacteria which 

 produce alkaline fermentation in urine, and in addition to the spe- 

 cies above mentioned has described the following : Urobacillus Pas- 

 teuri, Urobacillus Duclauxi, Urobacillus Freudenreichi, Urobacillus 

 Madcloxi, Urobacillus Schutzenbergi. 



Viscous fermentation. A special fermentation which occurs 

 sometimes in wines, and in the juices of bulbous roots containing 

 glucose, and in milk, is produced by various bacteria. One of these 

 is a micrococcus which has been described by Conn under the name 

 of Micrococcus lactis viscosus. The fermented juices become very 

 viscous, owing to the formation of a gum-like product resembling 

 dextrin; at the same time mannite and CO 2 are produced. The 

 gum-like substance, called viscose by Bechamp, is soluble in cold 

 water and is precipitated by alcohol. Guillebeau (1892) has de- 

 scribed a micrococcus and a bacillus which produce viscous fer- 

 mentation in milk Micrococcus Freudenreichi and Bacillus Hessi. 



