130 THE EVOLUTION OF LIFE 
it was one which proved fatal to Bacterzum termo, 
Torule, and other forms. 
The powerfully stimulating influence of a tem- 
perature of 122° F. may also be easily seen in 
another way. In addition to causing certain fluids 
to ferment which would otherwise remain barren at 
ordinary temperatures (77°-86° F.), it shows its 
influence upon those fluids which will ferment 
at these lower temperatures, by bringing about 
such a change with much greater rapidity. 
No fluid serves better for showing these relative 
effects than urine which has been neutralised with 
liquor potassz before the process of boiling, because, 
though it will mostly ferment at the lower incu- 
bating temperatures, it does so with difficulty and 
only after many days. Thus, I have found that a 
urine whose acidity required ten to twelve minims 
of liquor potassze per ounce for neutralisation, would 
(after such admixture and an ebullition of five 
minutes’ duration) not ferment under 12-15 days, 
if kept at a temperature of 70°-73° F., though such a 
change would show itself in 15-30 hours at a tem- 
perature of 122° F. 
It was also in the summer of 1875 that I first 
made these experiments to ascertain whether, as 
with other acid fluids, the fermentability of urine 
would be increased by previously neutralising it 
with liquor potasse. This preliminary inquiry was 
soon answered in the affirmative. 
Then came the more important question as to 
the cause or mode of production of such increased 
fermentability. For two reasons urine seemed to 

