CONDITIONS FAVOURING FERMENTATION. 53 



Six trials with neutralized potato-in^Msiou, having a specific 

 gravity of lOLl, yieldeJ no evidence of fermentation. Twice in- 

 fusions were heated to 248° F. (120° C), and four times to 230° F. 

 (110° C.) for 30 minutes. 



Sixteen trials with a neutral cucumher-m^{lsiol^l, having a specific 

 gravity of 1003, heated to temperatures varying from 221°- 

 248° F. (105°-120° C.) for 20 minutes were also attended by uni- 

 formly negative results. 



But in forty experiments with good cows' milk heated in closed 

 tubes half full of air to 280° F. (110° C.) for 5-60 minutes, and 

 also in five other experiments in which the milk was heated to 

 240° F. (115°*5 C) for 10 minutes, fermentation more or less 

 marked occurred in each case in from 2-10 days. 



The great variation in these results, especially with difi['erent 

 fluids similarly heated, makes it seem almost impossible to account 

 for them solely by reference to the death -point of germs, as some 

 will doubtless attempt to do. Why should this death-point be 

 so difi'erent in difierent fluids ? 



Then, again, these new experiments, like those which I have 

 previously recorded, will be found entirely to contradict Prof. 

 Cohn's position, that Bacillus is the only organism which ap- 

 pears when boiled or superheated fluids ferment. If it is true, 

 as he says, that other organisms are all killed by temperatures 

 below 212° F. (100° C), when they are immersed in fluids, how 

 are we consistently to explain the appearance of Micrococci and 

 of Torulse, some of which have been enabled to develop into typical 

 and well-formed mycelia ? The conditions and modes under which 

 these difi'erent organisms appeared are now to be described. 



VII. Si^ns of Fermentation in the Boiled and Superheated Fluids 

 employed in the foregoing Experiments. 

 TJrine. — The turbidity caused by precipitated phosphates will 

 never, by the experienced worker, be confounded with that due 

 to fermentation. He should, indeed, as far as possible, and ex- 

 cept for special purposes, avoid dealing with urines which are 

 prone to manifest this phenomenon. Sometimes in a slightly 

 acid urine such a deposition takes place even before the urine 

 attains the boiling-point, though at other times it only shows 

 itself very slowly after the fluid has begun to boil. In urines 

 of this latter type, it often happens that no clouding of the 



