Putrefactive Fermentations 117 
almost wholly be¢ause the taste is unpleasant to 
the ordinary palate. A large amount of lactie acid 
is, perhaps, injurious to young and delicate or weak 
digestive organs, but ordinarily is harmless. Lactic 
acid fermentations are extremely important in the 
processes of both butter and cheese manufacture, 
and their relations to these processes will be dis- 
cussed in detail in the proper place. 
Fermentations affecting the albuminoids.—These in- 
clude ordinary putrefactive fermentations, peptogenic 
fermentations, and fermentations resulting in the for- 
mation of poisonous products. These fermentations, 
as a rule, do not thrive in the presence of a strong 
lactic fermentation, so that ordinarily they do not 
manifest themselves in milk’ unless the conditions are 
peculiarly favorable for their development and un- 
favorable for the development of lactic acid. Many 
of the putrefactive fermentations will go on at a 
lower temperature than the lactic fermentations do; 
hence it is often found, when milk is kept at a low 
temperature in order to keep it from souring, that 
after a certain time it becomes bitter or foul-smell- 
ing. This condition is caused by some one of the 
characteristic putrefactive fermentations. The putre- 
factive germs also readily take on the spore form, 
and in this condition are not so readily killed by 
heat. The putrefactive fermentations usually result 
in the formation of bitter or other unpleasant flavors 
and disagreeable odors, and they are frequently ac- 
companied by a considerable evolution of gas. Pep- 
togenie fermentations are those which exert a pep- 
