NUMBER AND SOURCE OF BACTERIA IN MILK 249 



authorities it is suspected that a relationship exists between 

 certain types of streptococci of milk and scarlet fever, as 

 well as sore throats and intestinal troubles, in persons 

 consuming milk containing these forms of bacteria. 



In addition to these pathogenic bacteria, which are only 

 met with where the udder or parts of it is affected with 

 some form of disease, milk contains certain kinds of non- 

 pathogenic bacteria which have obtained an entrance to 

 the lactiferous sinus or milk cistern and some of the ducts 

 by way of the orifice in the teats. Generally speaking, 

 they are most abundant in the milk accumulated in the 

 lowest parts of the udder, and therefore obtained in 

 quantity in the first milk drawn from it in the milking 

 process. t The number of species present in the milk in 

 the udder are very few, the commonest being forms of 

 streptococci, which are apparently innocuous and present 

 in many cows which are quite healthy. They may be 

 looked upon as more or less normal inhabitants of the 

 milk ducts. Probably others obtain an entrance in the 

 same way, but find the conditions unfavourable for their 

 further growth and development, and consequently die out. 



Many investigations have been made to determine 

 the bacterial content of the milk which is drawn from 

 healthy cows, the outsides of whose udders have been 

 carefully brushed and washed and the milker's hands 

 washed with antiseptic solutions to prevent the addition 

 of bacteria to the milk from these sources. The milk 

 first drawn is found invariably to contain considerable 

 numbers of bacteria ; Harrison obtained in one c.c. of 

 such "foremilk" from 18,000 to over 50,000, Schultz 

 as many as 97,000, while the investigations of Orr and 

 Moore showed an average content of 3000 to 8000 

 per c.c. 



