188 THE EVOLUTION OF LIFE 
large number of experiments with fresh urine, passed 
into superheated vessels with all the precautions 
dictated by Pasteur and by Lister. These experi- 
ments dealt with two points in particular: first the 
effects of mere high incubating temperatures upon 
such a fluid (which we are to consider in this 
section) ; and, secondly, the effects of high tempera- 
tures when combined with different proportions of 
liquor potasse, which will be referred to in the next 
section. 
I found that pure urine, passed with all precau- 
tions into a flaméé vessel and protected from con- 
tamination, would, as Pasteur and Lister have 
said, remain pure if kept at a low temperature of 
about 70° F. (21° C). 
But if, in other pure vessels, some of this urine 
was put into an incubator maintained at a tempera- 
ture of 113° F. (45 C.), I have over and over again 
found that the urine in such vessels would become 
turbid within three days, and on examination 
would be found to contain myriads of Micrococci 
only. 
On the other hand, pure urine in pure vessels if 
maintained at an incubating temperature of about 
116 F. (47° C.) would not yield Micrococci. 
The fluids would under these conditions, either 
remain unchanged, or, the acidity of the urine being 
low, they would become turbid and swarm with 
Bacilli. For the appearance of micrococci in urines 
to which no liquor potasse has been added, the 
fluids must be exposed to the lower incubating 
temperature. 

