EXPERIMENT STATION BULLETINS. 273 



Illustrate what I have already found to run very uniformly in a dozen or more 

 trials. 



The cultures used were made by inoculating 100 c.c. litmus milk in Ehrlenmeyer 

 flasks of 250 c. c. capacity with very dilute cultures of A and B, made by diluting 

 1/. c. c. bouillon culture in 100 c. c. of physiologic salt solution and using definite 

 quantities of this for inoculating. A+B received of A the same amount as culture 

 A, and of B the same as culture B, that is, 



A=V2 c. c. of diluted bouillon culture A, 24 hours old, in 100 c. c. litmus milk. 



A:=iv, c. c. of diluted bouillon culture B, 24 hours old, in 100 c. c. litmus milk. 



A+B=i{. c. c. of diluted bouillon culture A, 24 hours old, +14 c. c. of diluted 

 bouillon culture B, 24 hours old, in 100 c. c. litmus milk. 



The gross changes in the milk may be indicated by the following scheme, tem- 

 perature 20°-22° C. throughout: 



20 hours after inoculation. 



A=No change other than very slight reddening of litmus. 



B:=No change apparent in the milk. 



A-|-B=L.itmus redder than in A, but not so very marked. No change in milk. 



J/J) hours after inoculation. 



A=:Litmus red. No other change in milk apparent. 



B==No apparent change in the milk. 



A+B=Litmus reduced except very thin red stratum of surface.. Firm curd. 



68 hours after inoculation. 



A:=Litmus red throughout, no other change in milk apparent. 



B=:Very slight peptonization on immediate surface, but otherwise unchanged 

 to eye. 



A+B:=Firm curd with whey separated. Litmus reduced except on immediate 

 surface, where it is red. 



92 hours after inoculation^ 



A=Litmus red throughout. No other change perceptible. 



B=:Milk peptonizing rapidly. Litmus is reduced in spots. 



A+B^Firm curd with whey separated as in 68 hours. Litmus has become red 

 throughout, probably through checked growth of micro-organisms and the perme- 

 ation of curd by oxygen. 



116 hours after inoculation. 



A^Litmus red in upper half, lower half reduced. Milk is heginning to lopper. 



B=Almost completely peptonized. Litmus reduced except in spots on surface, 

 where it is still blue. 



A-fB^Same as at 92 hours. 



l-'fl hours after inoculation. 



A=Curd separated from whey. Litmus reduced throughout except layer on 

 surface. 



B=Milk peptonized and slimy. Litmus blue on surface. 



A+B=Sam"e as at 92 hours. 



If the loppering of the milk be any criterion to the change taking place in A 

 and A+B, then there must be a difference of seventy-two hours for A+B first 

 manifested signs of loppering at 44 hours after inoculation and A did not begin to 

 lopper till the llCth hour after inoculation. By following the changes as recorded 

 above, the differences are plainly evident. 



In the second series the temperature varied between 23° and 24° C, two to three 

 degrees higher than the preceding test. I am satisfied, even at this writing, that 

 I am going to find material modifications with the changing of temperatures, but 

 as yet I am not ready to report on the temperature studies with these two micro- 

 organisms. 



The second series: 



23 hours after inoculation. 



A=;Litmus slightly reduced at the bottom, otherwise red. No change in the milk. 

 B=Litmus blue and unchanged. 



35 



