FACTORS INFLUENCING QUALITY 385 



This is particularly true in summer when the cows are on 

 pasture. This germ does not produce heat-resisting spores and 

 is therefore easily killed by high temperature. Although this 

 organism is the one which sours milk and is so abundant in 

 buttermilk, which is a good beverage for both adults and infants, 

 it does not follow that a medium number in milk supposed to 

 be sweet would be beneficial to the child. Milk fed to young 

 animals, whether child, chicken, pig or calf, should be thoroughly 

 sweet or fully sour. 



The second most common class of bacteria found in milk is 

 that known as the Colon group, " Bacilli Coli." There are 



a <b°Q*> ° o 

 °o n O O 



„ esn o a 



^. n o 00°^c 



A«i»S$ 



° ■ a 00 *' 



Fio. 124. — Milk as it appearB under the microscope. The clear, round fat globulea 

 are intersperwed with bucteria. Note relative Hmallness of the germs, also that the bacteria 

 ure grouped in clusters. Sec also Fig. I 26, page 888, 



several varieties of this class of organisms. Some have power 

 of free movement, others have not, however, none of them have 

 the power of forming within themselves spores so resistant to 

 heat that even boiling may not destroy them. They also pro- 

 duce gas while growing. It is the distending effect of the gas 

 produced by the growth of those bacteria which causes the pain 

 to infants suffering from cholera infantum and similar intes- 

 tinal disturbances. The natural habitat or home of this class 

 of bacteria is the intestinal tract of all higher animals, espe- 

 cially cows, and they gain entrance into the milk through par- 

 ticles of manure which accidentally fall into the pail during 

 milking. Many other methods of entrance are possible, e.g., 

 from poorly washed pails, or even nursing bottle and nipple, 

 25 



