BACTERIA AND MILK FERMENTATIONS 27 
the lactic organisms and for this reason milk infected 
with them sours with great difficulty. 
The action of this class of bacteria is to increase the 
viscosity of milk, which in mild cases simply assumes a 
slimy appearance. In extreme cases, however, the milk 
develops into a ropy consistency, permitting it to be 
strung out in threads several feet long. 
Slimy or ropy milk cannot be creamed and is therefore 
worthless in the manufacture of butter. Such milk should 
not be confused with gargety milk which is stringy when 
drawn from the cow. The bacteria belonging to this class 
are easily destroyed as they do not form spores. 
3. GASSY FERMENTATION. 
This is an exceedingly troublesome fermentation in 
cheese making and is also the cause of much poor flavored 
butter. The gas germs are very abundant during the 
warm summer months but are scarcely noticeable in 
winter. Like the bitter germs, they are antagonistic to 
the lactic acid bacteria and do not grow during the rapid 
development of the latter. They are found most abun- 
dantly in the barn, particularly in dung. 
4. TOXIC FERMENTATIONS. 
Toxic or poisonous products are occasionally developed 
in milk as a result of bacterial activity. They are most 
commonly found in milk that has been kept for some 
time at low temperature. 
5. CHROMOGENIC FERMENTATIONS. 
Bacteria belonging to this class have the power of 
imparting to milk various colors. The most common of 
