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"{'2) Bacteria irrow with the greatest readiness in milk and cream. 

 Hence they collect in milk and cream exposed to the air. and multiply 

 rapidly. In developing" they cause the milk to sour and curdle and 

 induce other changes in it. They also favor the ripening of cream, 



••(3) Vessels in which milk and cream are to be kept are a great 

 source of contamination by bacteria. The latter gather upon the 

 sides and in the joints, and devel()[) in the minute portions of milk, 

 grease, or other matters from which it is diflicidt to free the walls of 

 the vessels eoinpletely by washing. 



"(4) A large number of diii'erent species of bact^iria are found in 

 milk and cream. Dili'erent ^^]Jecies have ditt'erent effects. Most of 

 them sour and curdle milk at scmie temperature. A few induce 

 changes that render milk alkaline without the formation of curd. 

 "WTien a curd is formed it dili'ers in character with different species 

 of bacteria. The souring of milk is more complex than has been 

 supposed; and while without much doubt souring always depends 

 upon the action of bacteria, any one of a number of species, or several 

 combined, may be the cause. 



"(5) The longer a sj)ecimen of milk has been exposed to the action 

 of bacteria, other things being eiiual, the greater will be the number 

 of bacteria present. Hence it follows that cream will usually contain 

 a very large number. The presence of these organisms, so far from 

 being injurious, is of a positive advantage to the butter maker, since 

 it is by their action that cream is ' ripened.* 



"(6) The ripening of cream appears to be even more complex than 

 the souring of milk. AVhile the ripening of cream is undoubtedly 

 dependent upon the presence of bacteria, it is doubtful whether one 

 species can produce what is known as ripened cream. Dairj^men let 

 their cream ri])en before churning because their experience implies 

 that the butter separates ("comes") more readily, keeps better, and 

 is of better flavor. A plausible explanation is that the bacteria break 

 up the albuminous matter which encloses the particles of butter fat, 

 so that the butter is more readily separated from it, and when made 

 contains less of it. Since this albuminous matter affords support for 

 bacteria, which cause butter to become rancid, it is natural to suppose 

 that butter will keep the better the less it contains. 



"(7) Two important points in the handling of milk and cream are 

 brought out by these considerations : 



'* First. The importance of keeping milk, so far as possible, free 

 from bacteria and at a low temperature, in order that the cream may 

 all separate before the milk sours. 



'' Second. 1'he advantage of keeping cream under circumstances 

 favorable to the growth of the bacteria that induce ripening. 



"(8) In brief, vessels in which milk is to be kept for creaming or 

 for transport should be most carefulh^ cleansed before the milk is 



