EXPERIMENT STATION BULLETINS. 



533 



These analyses assist in understanding: what is going on during the develop- 

 ment of a culture of .^erm B in milk, and they also tell us that perhaps the 

 hydrolised products, amido bodies, or ammonia compounds may be the cause of 

 the hastened growth of the lactic germs. The fact that early in the development 

 of germ B, the lactic germs are stimulated, may mean that the caseoses are more 

 instrumental than the others; still from the beginning amido and ammonia 

 compounds are apparently produced in traces. It is impossible to draw any 

 definite conclusions from these analyses; only in a most general way do they 

 help to associate lactic development and proteolysis in this specific case. In 

 some other instances proteolysis does not seem to be able to accomplish this 

 favorable action on lactic germs. 



rV. THE POSSIBILITY OF ACID PUODUCTION IN MILK DURING TIIE EARLY STAGES OF 



DEVELOPMENT OF GERM B. 



This is a very important question to raise in connection with the associative 

 results of germ A and B, as it may be suspected at once that a small amount of 

 acid produced by germ B added to the acid known to be produced by germ A 

 may account for the associative result, and also a very slight increase of acidity 

 may hasten the work of any lab enzyme which may be present. In the latter 

 case the acidity of the mi.xed culture must be regarded as apparent and not real, 

 and the increase indicated would have to be accounted for by the action of 

 germ B on the indicator which may be regarded as a feasible explanation. 



As cultures of germ B age, they become more and more alkaline. This can- 

 not be gainsaid for it is very apparent by the use of litmus as aij indicator. 

 With phenol-phthalein as indicator, an increased acidity would be noted, but 

 this is probably due to the destructive action of the germs upon this indicator. 

 When germ B is grown in litmus milk the blue of the litmus changes to a dirty, 

 reddish blue, then it completely disappears, but after the greatest activity of 

 the germs subsides, distinctly blue patches reappear upon the immediate surface 

 of a flask culture. It can be seen from this that if the changing of blue litmus 

 to a reddish blue and the apparent increase of acidity by means of phenol- 

 phthalein is in reality due to acid formation then the matter is settled at once, 

 hut the litmus becomes more decidedly blue as the culture in milk ages, if added 

 in sufficient quantity at the time of testing; and the phenol-phthalein indicator, 

 when this strong alkalinity is so pronounced with added litmus, marks a higher 

 acidity. There is this, too; litmus or phenol-phthalein allowed to stand in the 

 old culture a very short time is destroyed and will manifest no response. Other 

 indicators employed give no better results. What then may be concluded under 

 such circumstances? It is our purpose to bring together a few observations to 

 enable us to form a satisfactory understanding. 



In order to obviate the difficulties experienced in the use of milk culture for 

 the determination of acid formation and to furnish a clear, transparent medium, 

 saccharine bouillon cultures were utilized to study reaction changes. Bouillon 

 of the same lot was divided into several portions, to each of which was added 

 one of the following sugars: Saccharose, dextrose, lactose, levulose. Inocula- 

 tion of each was made at the same time with the same number of germs. A 

 soluble starch bouillon was also added to the list. So far as could be observed, 

 the reaction began to change in the direction indicated in the table until the 

 tenth day, when the results were recorded. 



Saccharose bouillon 

 Dextrose bouillon.. 



Lactose bouillon 



Leviilose bouillon.. 

 Starch bouillon 



In starch there is evidently no reduction in acidity but in the other cases, with 

 the exception of levulose, it is quite apparent. The starch had undergone change 



