526 



STATE BOARD OF AGRICULTURE. 



unstable, irrespective of germ life. Again, there was the possibility of finding that 

 milks from different cows would respond differently to the influence of the same 

 germ, even when sterilized within one hour after drawing. To arrive at some 

 definite knowledge concerning these points, the writer began by testing milk as 

 secured from the dairy and employed in the laboratory. 



In testing milk, as it is obtained from the dairy, for cultural purposes, it has 

 been noted in this laboratory that when subjected to heating at 



20° it sometimes loppers and sometimes does not, 

 21° it sometimes loppers and sometimes does not, 

 22° it sometimes loppers and sometimes does not. 



Of course 22° milk is far more likely to lopper than 20° milk, but in this instance 

 it is not the customary action which should be considered, but the uncustomary, 

 for it is the deviation from normal conditions sought. 



Bacteriologists have been aware of discrepancies occurring in milk culture work 

 for some time, and have been somewhat at a loss to discover the cause for this. 

 The behavior of certain species in milk could not always be confirmed, and error 

 is the usual charge in a case of failure in confirmation. When irregularities do 

 occur or are found it were better to look for the specific reasons than to turn 

 it off as unfathomable and personal. The author does not wish to express or 

 draw any positive conclusions from his woi'k on the variations of milk, but finds 

 it essential to his studies with association; accordingly, he is compelled to give 

 the results of experiments conducted up to this time. 



Three lots of milk were secured from the dairy at different times and were 

 labeled as fresh, fresh dairy, and old dairy milk. The fresh was obtained from 

 the stable, separated and sterilized within one hour after coming from the 

 cow. The fresh dairy milk had been skimmed in the dairy and is what would 

 be regarded as ordinary sweet dairy milk. The old dairy milk had been skimmed 

 and stood in the dairy some time and had taken an upward start in acidity. 

 These different lots were flasked, using an equal amount for each flask, and ster- 

 ilized by the discontinuous method. After sterilization, into each flask was placed 

 one c. cm. of a 1: 1000000 dilution of a bouillon culture of germ B. These high 

 dilutions of cultures have been found throughout our work as necessary to satis- 

 factory measurement. When these jnilk cultures had stood for a time, a portion 

 was tested by heating to determine whether it would curd or not, and at what 

 point of time such curding would take place with the different lots of milk. 

 This was instigated by the experience with germ B which was learned to produce 

 curding in some milks in the cold but always by heating, at some stage. The 

 following table will give the results: 



Original milk designated as — 



Original 

 acidity. 



Fresh (stable). 

 Fresh (dairj')-' 

 Old (dairy).... 



19° 

 20° 

 21° 



Temperature 

 maintained C. 



21° 

 21° 

 21° 



Time of 



loppcring by 



heating. 



50 hours 

 47 lioiirs 

 42 hours 



-Acidity 

 at time of 

 loppering. 



19° 

 20° 

 21° 



Two explanations for these differences are possible; the one, that germ B 

 produces a certain amount of acid which in addition to that already present is 

 sufficient to lopper the milk, earlier in the more acid milk when subject to heat, 

 and later in the less acid; the other, there is formed an enzyme of products 

 which in the presence of the acid of the more acid milk, manifests itself sooner 

 when heat is applied. We assume in this case that the enzyme acts before 

 sufficient heat has been applied to destroy it. Some space will be given later to 

 the discussion of the possibility of an increased acidity in the development of 

 germ B; consequently, it is unnecessary to enter into the question at this point 

 other than to say that evidence in its favor appears meager. A very old culture 

 of germ B, strongly alkaline, will throw down an abundant precipitate upon 

 heating, and in most milks, cultures of germ B have to be well under way 

 before curding will take place by the application of heat. If there is any ques- 



