EXPERIMENT STATION BULLETINS. 



525 



This single test corresponds very favorably with the usual results obtained and 

 is very representative. Milk for both cultures should bo made from the same lot. 



(c) By a comparative determination of the number of lactic bacteria in culture 

 A and in culture A + B, at the time of the loppering of A + B and when germ B 

 has completely disappeared. The ratio may be expressed as follows: 



A : A + B : : 27 : 1C14. 



It has been also possible to demonstrate that germ B produces stable products 

 which withstand sterilization and exert the same influence over germ A in milk 

 cultures as the living germs themselves. Again this may be shown in a very 

 similar manner as employed in the previous series: 



*(a) By observing the milk cultures made from the same lot of milk and noting 

 that culture (A + the products of B) loppers the milk as many as seventy-two 

 hours earlier than culture A. With litmus milk it is possible to follow out the 

 progress by the changes taking place in the litmus from the formation of acid. 



(b) By a comparative study of acidity of culture A and culture ( + the products 

 of B). 



Flask-cultures. 



Same lot of milk: 



n 



2 



3 

 4 



51 

 6 

 7 

 8 



Germ A. 



Germ .A. + products of germ B. 



96 hours 

 old. 



66° 

 66° 

 64° 

 66° 



112° 

 110° 

 110° 

 110° 



(c) By a comparative estimate of the number of germs in culture A and in 

 culture (A + the products of germ B). The ratio may be expressed in the fol- 

 lowing manner: 



A : ( A + products of germ B) : : 27 : 1007. 



Even at the present time there is no reason for altering these figures or results 

 in the slightest degree. Repetition over the past year only confirms the conclu- 

 sions reached in our previous article. However, in our work at that time there 

 were evident some pecularities which could not be satisfactorily explained; in 

 the previous work, irregular results were obtained usually from the employment 

 of different lots of milk in conducting a single test. For the time being this 

 matter was allowed to rest and in the tests the same lot of milk was used and 

 treated in precisely the same way. 



II. THE SIGNIFICANCE OF DIFFERENT MILKS AND THE RELATION OF VARIABILITY TO 



GERM DEVELOPMENT. 



Since it was so plainly indicated in the work with the products manufactured 

 by germ B in milk after a few hours growth that the lactic germs responded 

 favorably to their influence, it was suspected that ordinary milks contained germ 

 products in greater or less quantities, some favorably influencing the growth of 

 the lactic germs, others being indifferent, and still others antagonizing. These 

 were considered a probable cause for the irregular results secured from somewhat 

 varying or different milks. These products could be regarded as cleavage products 

 resulting from the action of the germs upon the constituents of the milk, secre- 

 tions of the germs, or a possible dissolution of the milk which is known to be very 



*The products were secured by sterilizing forty-eight hour culture. See second article. 



