16 
' BACTERIOLOGY. 
beer and wine, the clotting of milk by bacteria in 
making cheese, the fermenting of cabbage in making 
sauerkraut. 
It may be well to mention here certain substances 
that are formed principally in the decomposition of 
meat and fish by bacteria. They are called ptomaines, 
and are present in partially decomposed animal and 
vegetable matter. Some of them are highly poisonous. 
The most common poisonous ptomaines are those 
found in partially decomposed meat, fish, and ice-cream. 
