32 RlBPOUT OF THE BACTERIOLOGIST OF THE 



molds to grow in the milk and produce changes in its composi- 

 tion. This should not take place to an appreciable extent under 

 twelve hours, and if the temperature is kept reasonably low, 

 will not do so for a much longer period. 



From this it will be seen that in the milk as it is ordinarily 

 delivered in the milk trade of the smaller cities or at the fac- 

 tories there should be no odor due to plant growth. Whenever 

 a disagreeable odor is present it can be ascribed either to 

 aromatic substances absorbed or to holding the milk at too high 

 temperatures. 



This statement of the matter may at first glance appear to 

 conflict with practical observation; for sometimes a certain odor 

 becomes noticeable soon after the milk is drawn and appears to 

 increase in the cheese curd. In this case it would be more in 

 accord with the known facts to assume that the same class of 

 bacteria which brought about the decomposition of the excreta 

 in the barn and produced from them the vile odor which was 

 absorbed by the milk also found their way into the milk itself 

 and there, later, produced similar foul smelling compounds. 



Under ordinary circumstances we can begin to reckon the 

 twelve hours above mentioned, from the time the milk is drawn; 

 but the interesting observations of Moored and Ward^ have im- 

 pressed the fact that in some animals the bacteria work their way 

 high up into the glandular tissue of the udder and convinuously 

 attack the milk as it is formed. 



Animal and absorbed odors are to be avoided as far as pos- 

 sible, since they are never desirable. After they have once 

 entered the milk aeration will assist in their removal. The pro- 

 cess of pasteurization accompanied by a subsequent cooling of 

 the milk by flowing in a thin sheet over a cold surface is recom- 

 mended by some producers of fine dairy products as a means 

 to the same end. 



'Moore, V. A., and Ward, A. R. Source of Gas and Taint-Producing 

 Bacteria in Clioeso Curd. Cornell Ajir. Exp. Stn., Bui. 158, 1899. 



"Ward, A. R. The Invasion of the Udder by Bacteria. Cornell Agr. 

 Exp. Sta., Bui. 178, 1900. 



