PRODUCTS OF VITAL ACTIVITY. 141 
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 
Maddoxi, 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, are produced. The 
gum-like substance, called viscose by Beéchamp, 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. 
A micrococcus producing viscous fermentation in milk has also 
been described by Schmidt-Miihlheim, and a bacillus by Léffler. 
Bacillus mesentericus vulgatus also produces a similar change in 
milk. 
Marsh gas, CH,, is produced by the fermentation of cellulose, 
through the action of microédrganisms the exact characters of which 
have not yet been determined. According to Tappeiner, there are 
two different fermentations of cellulose. The first occurs in a neu- 
tral one-per-cent flesh extract solution to which cotton or paper pulp 
has been added. The gases given off are CO, and CH, and small 
quantities of H,S. The second fermentation occurs when an alkaline 
solution of flesh extract containing cellulose in suspension is used. 
The gases formed are CO, and H. In both cases small quantities of 
aldehyde, isobutyric acid, and acetic acid are produced. 
Hydrosulphuric acid, H,S8. This gas is produced during the 
growth of certain bacteria. The conditions governing its develop- 
ment have been studied by Holschewnikoff, who experimented with 
two species, one isolated by himself and one by Lindenborn, named 
respectively Bacterium sulfureum and Proteus sulfureus. The first- 
mentioned bacterium, when inoculated into eggs, produced within 
three or four days an abundant quantity of H,5; the other did not. 
Upon raw albumin both species produced but little, and on the yolk 
of egg aconsiderable amount of this gas. Upon cooked egg the 
action was the reverse. In peptone-bouillon the evolution of H,S 
was abundant ; in the absence of peptone, very slight. 
Putrefactive fermentation. The putrefactive decomposition 
of albuminous material of animal and vegetable origin is effected 
by a great variety of microdrganisms and gives rise to the forma- 
