will in all cases remedy the evil to a large extent.  With this knowledge in hand the avoidance of all these troubles is only a question of care in handling the dairy.  It must be recognised that most of these troublesome bacteria come from some unusual sources of infection.  By unusual sources are meant those which the exercise of care will avoid.  It is true that the souring bacteria appear to be so universally distributed that they can not be avoided by any ordinary means.  But all other troublesome bacteria appear to be within control.  The milkman must remember that the sources of the troubles which are liable to arise in his milk are in some form of filth:  either filth on the cow, or dust in the hay which is scattered through the barn, or dirt on cows’ udders, or some other unusual and avoidable source.  These sources, from what we have already noticed, will always furnish the milk with bacteria; but under common conditions, and when the cow is kept in conditions of ordinary cleanliness, and frequently even when not cleanly, will only furnish bacteria that produce the universal souring.  Recognising this, the dairyman at once learns that his remedies for the troublesome infections are cleanliness and low temperatures.  If he is careful to keep his milk vessels scrupulously clean; if he will keep his cow as cleanly as he does his horse; and if he will use care in and around the barn and dairy, and then apply low temperatures to the milk, he need never be disturbed by slimy or tainted milk, or any of these other troubles; or he can remove such infections speedily should they once appear.  Pure sweet milk is only a question of sufficient care.  But care means labour and expense.  As long as we demand cheap milk, so long will we be supplied with milk procured under conditions of filth.  But when we learn that cheap milk is poor milk, and when we are willing to pay a little more for it, then only may we expect the use of greater care in the handling of the milk, resulting in a purer product.

Bacteriology has therefore taught us that the whole question of the milk supply in our communities is one of avoiding the too rapid growth of bacteria.  These organisms are uniformly a nuisance to the milkman.  To avoid their evil influence have been designed all the methods of caring for the dairy and the barn, all the methods of distributing milk in ice cars.  Moreover, all the special devices connected with the great industry of milk supply have for their foundation the attempt to avoid, in the first place, the presence of too great a number of bacteria, and. in the second place, the growth of these bacteria.

Bacteria in butter making.