2l6 ILLINOIS DA'RYMEN'S ASSOCIATION. 



to the air, is so comparatively small that they are not necessarily going t( 

 create trouble' often in the after manipulations of the milk, provided 

 those manipulations are such as will tend either to hold these bacteria 

 in check or to overcome them by one method or another. Exceptions to 

 this must be taken, whenever disease producing bacteria or pathegenic 

 bacteria are present, since, of course, we all recognize the possibility of 

 transmission. But, in this article we are not considering the matter of 

 disease because our mind is occupied with matters which are closely 

 related to milk and its products. We may, therefore, assume that the, 

 bacteria which exists in the udder of a cow will not cause any serious 

 trouble if a little care is exercised. 



The germ content of milk immediately after milking is usually greatly 

 increased and this increase is exceedingly variable. This doubtless has 

 been brought out by Dr. Russell in his paper on the " Contamination of. 

 Milk," and he probably stated the sources of these bacteria which find 

 their way into milk. It is desirable to keep the number of bacteria down 

 to its minimum, otherwise it will be exceedingly difficult to control the 

 bacteria which have been introduced by the various methods available, 

 even by starters. Different devices or different methods may be em- 

 ployed to reduce the number of bacteria and to keep them within certain 

 limits and will render the dairyman inestimable service in his control of 

 the milk. There might be a difference of opinion as to the most desirable 

 method to keep the number of bacteria down, but there can be no 

 difference of opinion as to the desirability of diminishing the number, 

 since, as we shall see later, the activity of the germicidal agents is largely 

 influenced by the number of bacteria present. 



2. Germicidal Constituents of Milk. — Intimately associated with the 

 germ content of milk are the germicidal constituents, for one depends 

 upon the other for its manifestations. Considerable study and attention 

 have been given to these substances as they exist in nearly all the body 

 tissues and body secretions, of late year, inasmuch as they are associated 

 with susceptibility to and immunity against disease. It is therefore 

 natural that we should find these agents existing in the milk and attribute 

 to them their proper significance. That they exist can be easily shown 

 by simply ascertaining the number of bacteria in the milk at. the time of 

 milking and each hour afterward for about twelve hours. It will be found 



