730 Reading-Course for Farmers' Wives. 



The lactic fermentations, or common " souring " of milk is brought 

 about by a number of species of bacteria. Formerly it was supposed 

 that a single species produced this change, which consists in the splitting 

 of the milk-sugar molecule into carbon dioxid and lactic acid. It is 

 now known, however, that in this process of splitting up the milk-sugar, 

 other by-products are produced. In the simple lactic type of fermenta- 

 tion these secondary products are not very important. It should be 

 noted, however, that in the souring of milk by different species of bac- 

 teria, correspondingly dififerent by-products may be produced. In conse- 

 quence of this, the souring is often accompanied with by-products that 

 are undesirable if not injurious to the consumer. In these cases the 

 deleterious substances are often produced -before the quantity of acid 

 is sufficient to cause curdling. In fact, these by-products may become 

 harmful while the milk is still considered sweet and wholesome. The 

 most telling truths which come to us from all these inquiries are that 

 different bacteria causing souring in milk produce very different effects 

 upon the milk itself as shown in the rapidity of the souring and in the 

 types of fermentation accompanying it. 



Much has been written concerning disease-producing bacteria in milk. 

 These belong to two distinct classes, namely : ( i ) The specific bacteria 

 of certain diseases of cattle, which may, if the animal is suffering from 

 disease, gain entrance to the milk. In this class may be mentioned 

 tuberculosis, foot-and-mouth disease and possibly anthrax, (2) The 

 bacteria of certain human diseases, such as typhoid fever and diphtheria 

 and the virus of scarlatina and measles. A very large number of epi- 

 demics of these diseases has been traced to the milk supply through 

 which the infections occurred. The explanation of this is that in ca'=es 

 in which these diseases existed among the attendants or in their homes, 

 sufficient care was not taken in handling the milk to prevent the entrance 

 of the germs of these diseases. In case of typhoid fever, the water used 

 in rinsing the utensils may be contaminated. In cases of diphtheria it 

 often happens that those who have recently apparently recovered from 

 the disease, but who still have the bacilli in their throats, are engaged in 

 milking or in otherwise handling the milk, where by sneezing or coughing 

 these bacilli may escape from the throat into the milk. The sad experi- 

 ences of the past are teaching the importance of taking reasonable pre- 

 cautions against the prevention of such maladies. 



In cases when bowel trouble, especially in children, follows the use of 

 milk containing many bacteria, the immediate cause is quite as likely to 

 be the effects of the acids and other by-products which have been pro- 

 duced in the milk by various forms of bacteria, as by the activities 



