538 BOAED OF AGEICULTUEE. 



ence, if particular notice is taken, we see the importance of removing the 

 milk from the odors of the stable as soon as it is milked. 



Second. There are the defects produced by the presence of living 

 micro-organisms. Before taking up the treatment of milk to avoid this 

 class of defects, it may be helpful to enter into a discussion and explain 

 a few fundamental principles that govern bacterial life, in order to make 

 it comprehensive why milk should be treated in this manner. All animal 

 and vegetable matter if exposed to air at ordinary temperature undergoes 

 some change. These changes are familiar to all of us, and are known 

 as fermentation, decomposition or decay. The most common change that 

 occurs in milk is souring. The souring of milk is due to the action of 

 minute organisms, known as germs or bacteria. These bacteria are so 

 minute that they can be seen only by the aid of a powerful microscope. 



Besides the ordinary soui'ing of milk, there are many other changes 

 that may take place, such as the ripening of cream, the curing of cheese, 

 rancidity in butter, ropiness, blue or red milk and many other changes 

 less common. In the case of milk these changes are called fermentation, 

 because they are similar to the fermenting of cider or vinegar. The term 

 includes, also, changes due to unorganized ferments, such as action of 

 rennet and pepsin, besides those of bacteria. But since these unorganized 

 ferments play such a small part in the case of milk we need not consider 

 them. There are three essentials for the development of bacterial life 

 that need to be mentioned. These are food, warmth and moistm-e. Dark- 

 ness aids their development, but direct sunlight is fatal to such life. In 

 a dairy we have all the conditions for growth. For the reason that milk 

 is a complete and easily digested food for man, it likewise is a good me- 

 dium for l>acterial growth. They thrive within wide limits of tempera- 

 ture, but 90 deg. to 93 deg. F. seems to be the most favorable tempera- 

 ture for rapid development. At this point a large number are capable 

 of reproducing themselves every twenty minutes. To illustrate, we esti- 

 mate that at 93 deg. bacteria increase 200-fold, while at 55 deg F. only 

 eight-fold. At 40 deg. they become inactive, but still retain life. The 

 majority can even withstand freezing. From this we can gather the rea- 

 son why it is necessary to keep milk at a temperature where bacterial life 

 is inactive in order to prevent any radical change. Heat has the same 

 effect as cold to a certain degree, however. At 212 deg. F., which is the 

 boiling point, all germs except those that are in a spore form are de- 

 stroyed. It is, therefore, of great necessity to subject all dairy utensils 

 to a boiling temperature for at least ten minutes before they are really 

 in a sanitary condition. All dairy utensils should be made of tin or like 

 metal, with all joints smoothly flushed with solder to prevent crevices 

 which serve as breeding places for bacteria. 



Keep the cows in a stable by themselves. Ventilate, light and drain 

 your stable well. Have the floors water tight and the walls of plain 

 construction. Avoid all breeding places. Use no dusty or mouldy litter 



