174 AGRICULTURE OF MAINE. 



ditional fact that milk is one of their favorite foods, and the 

 possibilties of trouble from them about the dairy loom large. 



Scattered everywhere throughout nature are these invisible 

 bodies, living, dying and propagating their kind ; some of them 

 beneficial, some of them harmless, some of them dangerous to 

 health and some merely troublesome. About barns and dairies 

 always throng those known as the lactic acid germs, waiting to 

 sour our milk. These it is impossible to exclude. The problem 

 here is to keep as many as possible out of the milk, and to keep 

 those that do enter from multiplying. About the barn are al- 

 ways the filth bacteria from the cow's intestines, living and 

 thriving in the manure; and the comparatively harmless bacte- 

 rial flora of the hay. Then, in addition to these regular inhab- 

 itants, very often chance visitors at times happen in, introduced 

 through carelessness or criminal negligence, or occurring as tem- 

 porary inhabitants of the dairy w^ater supply, or brought in on 

 the hands or person of some person handling the milk. 



The word "dirt" usually calls up to our minds a picture of 

 mud or earthy material of some kind; but this is a restricted use 

 of the term. Any foreign substance in or on a material renders 

 it dirty. A grease spot on a piece of cloth makes it just as dirty 

 as does a mud spot, and has the added disadvantage that it is 

 harder to get rid of. In this wider sense bacteria in milk are 

 capable of rendering it just as truly dirty as dust, hair, grit or 

 manure ; and this form of dirt is the more dangerous inasmuch 

 as it is invisible, and so we have no means of knowing its pres- 

 ence until it is too late. Between bacterial dirt and the dirt that 

 takes the form of manure, grit and hair there is a still closer 

 relation, for these forms of visible dirt are loaded with myriads 

 of bacteria, and, together with other forms of dirt, they con- 

 stitute the means of conveyance to, and of entrance into other 

 substances of the more dangerous and troublesome bacterial 

 dirt. If the visible dirt was all'that entered our milk it might 

 be possible to shut our eyes and drink, for the dirt itself would 

 do us little harm. 



Remembering these facts let us now consider the sources from 

 which dirt, in the commonly accepted sense of sand, dust, hair, 

 manure, etc., enters our milk. And in this consideration we 

 shall only take into account the possibilities that lie before the 

 milk before it leaves the hands of the producer. 



