No. 4.] MILK AND CREAM. 353 



Different breeds of eows, as is well known, give milk of 

 varying degrees of richness. Thus Guernseys and Jerseys 

 produce milk with the highest amount of total solids, and 

 Holsteins give milk with the lowest amount. Individual 

 cows, however, show wide differences, irrespective of breed. 

 It is not unusual to find individual Holsteins giving milk as 

 rich as some Jerseys. 



Puke and Impure Milk. 



Pure milk may be defined as the natural product of a 

 healthy cow, drawn and cared for in a cleanly manner. Milk 

 from diseased cows, or cows in a low physical condition, 

 cannot be considered as pure. Milk from cows affected with 

 tuberculosis of the udder is positively dangerous. There is 

 still a difference of opinion as to whether milk from cows 

 moderately affected with tuberculous lungs, glands or other 

 internal organs is positively dangerous, but in the light of 

 present knowledge, it must at least be viewed with suspicion. 

 Milk from some Holstein cows does not contain over 11.5 

 per cent of total solid matter, and 3 or even less per cent of 

 fat. Such milk, other things being equal, must be consid- 

 ered pure and health}', only not as rich as that from other 

 cows. Milk drawn from a healthy cow is perfectly sterile, 

 and if the proper precautions are taken, it is possible to keep 

 it for a considerable length of time without change. As soon 

 as the milk is drawn, conditions present themselves which 

 cause the milk to change and become impure. 



Impure milk may result from dirty cows, dirty stables, 

 dirty milkers and dirty milk pails. Milk absorbs a bad odor 

 very rapidly, and if left exposed to a bad atmosphere will 

 very soon become tainted. The primal cause of all the 

 changes which milk undergoes is the result of bacteria. 



What Bacteria are. 

 Bacteria may be defined as microscopic, one-celled plants, 

 belonging to the lowest plane of vegetable life. There are 

 three typical forms, the spherical, elongated, and spiral. 

 These forms may be likened to a ball, a short rod and a cork- 

 screw. Scientifically they are classed as coccus, bacillus and 



