ILLINOIS DAIRYMEN'S ASSOCIATION. 



account of their minute size their study is surrounded by many difficul- 

 ties. They multiply very rapidly by fiasion (splitting in two). Some 

 species change to the spore form when conditions are no longer favorable 

 for them to multiply, and in this state they can remain for a long time 

 and again come back to the vegetable state when conditions and sur- 

 roundings are favorable for their development. 



If we consider how rap'dly these germs multiply, we can form an 

 idea of the amount of damage they can do; under favorable conditions 

 the offspring of one single germ may be millions in twenty-four hours. 



The importance of preventing bacteria from getting in to the milk 

 and that of making the conditions of their development as unfavorable as 

 possible, must thus be apparent to every dairyman. 



Chemicals and heat are the only practical methods known for the de- 

 struction of bacteria. When in the vegetable state a temperature some- 

 what less than the boiling point will destroy them, but when they are 

 in the spore state a considerable higher temperature and applied for a 

 longer time, is required . 



The chemicals generally used f:)r this purpose are borax, salysilic 

 acid and formaldihide, or some preparation from them. It can be taken 

 for granted that if a chemical is of such a nature as to destroy germ 

 life, it is injurious to the human system and should therefore not be used 

 in connection with food products. 



Some species attack the sugar in the milk and some the albumi- 

 noids, while others exist and live in milk and apparently cause no change. 



The majority of bacteria develop very readily in milk and the tem- 

 perature at which they multiply most readily and thus taint the milk 

 most quickly is at blood heat, and the lower the temperature, that is, 

 the cooler the milk, the slower their development. 



Different bacteria taint milk differently, but the same species always 

 affect milk in about the same manner, and it is one of the methods for 

 the identification of different species. For instance, bacillus acidi lac- 

 tici always produce lactic acid (souring). Although Prof. H. W. Conn, 

 in the U. S. bulletin 25, office of Experiment Station, in speaking of lac- 



