(30 FERMENTS IN MILK 



for analytical or similar purposes. As low and high tempera- 

 tures are so effective in producing unfavorable conditions, these 

 should be chiefly employed in controlling the growth of micro- 

 organisms in the dairy industry. 



Kind of Germs Found in Milk. The number of species of 

 germs found in milk has not yet been definitely established, due 

 chiefly to the fact that it is in some instances difficult for bacteri- 

 ologists to differentiate one species from another. The descrip- 



FIG. 9. Shows a plate exposed one-half minute under a cow's udder treated with a 

 5 per cent solution of carbolic acid. (Bui. 87, Nebraska.) 



tion of one species of bacteria by two different bacteriologists 

 may vary considerably, as the characteristics of the germs 

 depend so much upon the conditions prevailing throughout the 

 classification process. Over 200 different species have been 

 described. It is possible, however, though all of these types 

 may have different morphological and physiological character- 

 istics as described by different bacteriologists, that some two or 

 more of the 200 types may belong to one species. 



