200 BACTERIA IN BUTTER. 



to the type of ripening that is desired. Such irregularities, 

 however, are comparatively few. The dairyman is inter- 

 ested in the practical results rather than the logic of his 

 method, and so long as he finds that, in the great majority 

 of cases, he can in this way easily obtain a starter that pro- 

 duces satisfactory results, he is quite satisfied with the 

 method. This use of natural starters began years ago for the 

 purpose of hastening the souring during cold weather ; but in 

 recent years it has extended more and more, until now it is 

 widely adopted by butter-makers who desire to make a high 

 grade of butter. 



When we recognize the great variety of bacteria that may 

 find their way into milk from ordinary sources, we are forced 

 to ask why natural starters should ordinarily be satisfactory. 

 The answer has been already given in the facts regarding 

 the growth of bacteria in milk. 



1. The bacteria which commonly find their way into 

 milk are mostly of the types which produce either favorable 

 action upon the cream or no action at all. The probability 

 is, therefore, that any sample of milk obtained under proper 

 conditions will be filled with bacteria, most of which are 

 favorable to the purpose for which the starters are wanted. 



2. Soured milk is commonly nearly a pure culture of lactic 

 bacteria. If allowed to sour at a temperature of 60-70 the 

 lactic bacteria rapidly get *the upper hand of the other 

 species present, and by the time the milk is distinctly 

 soured it will contain so nearly a pure culture of lactic 

 bacteria that the other species must be regarded as of com- 

 paratively little significance. Hence, the natural starter 

 prepared as described will be a quantity of milk filled 

 with typical lactic bacteria in great quantities, commonly 

 a single species of lactic organism, though frequently 

 there may be two or even three such species. It will 

 not always be the same type that has obtained the upper 

 hand, but some lactic bacteria are always in great pre- 



