on Milk and Milk-Products. 
383 
than the bacillus of lactic fermentation. Of the latter it has 
been said that it cannot exist without free oxygen, and that free 
access of oxygen stimulates its development. To the bacillus of 
butyric fermentation, on the other hand, free oxygen appears to 
be of little importance. Except in this one respect, the bacillus 
shows no difference from that which has been studied by others. 
The bacillus has the form of rods which are motionless while 
young, but after several divisions have taken place they 
commence to move about, either singly or in chains consisting 
of several individual cells. They appear to be attracted by 
solid nutriment, and adhere to it for a time rather firmly. They 
are from three to ten times longer than they are broad. The 
cells complete their growth in length first ; they afterwards 
increase in width, and lastly the spores are formed. The rods 
are either straight or curved. With regard to the influence of 
temperature, it has been found that a lower temperature retards 
and a higher stimulates the development, and consequently the 
fermentative action. The most suitable temperature has been 
ascertained to be 95° Fahr. ; at a higher temperature than this 
the bacillus is destroyed. The spores will stand a boiling 
heat for five minutes very well ; ten minutes interfere with 
them seriously, and a complete result is doubtful ; after fifteen 
minutes' exposure none survive. 
Alcoholic Fermentation. — It is generally known that by the 
addition of yeast to solutions of sugar extracted from plants, or 
produced by the conversion of starch, a decomposition is effected, 
the chief products of which are alcohol and carbonic acid. Alco- 
holic fermentation can be pronounced ?,s the most widely known, 
best studied, and most extensively applied process of its kind. 
In connection with milk, however, it is only within the last few 
years that any attention has been paid to it. 
What is known as yeast, when examined under the microscope, 
is seen to consist of small cells possessing all the characters of 
vegetable cells. The cells, which are generally oblong, augment 
by budding ; they are present in the fermenting liquid, either 
singly, or a few joined together, or a greater number forming 
chains. When introduced into solutions of those kinds of su»ar 
which do not readily undergo lactic fermentation, active alcoholic 
fermentation will be started in a very short time. On the other 
hand, those kinds of sugar which are split up into lactic acid 
without difficulty do not easily form alcohol and carbonic acid. 
To the latter class milk-sugar belongs, and it is therefore not 
surprising to find that little is heard of the alcoholic fermenta- 
tion of milk. 
There is indeed some difficulty experienced when trying to 
start alcoholic fermentation in milk. As is the case with butyric 
