
132 THE EVOLUTION OF LIFE 
after boiling, being the invariable result in his hands. 
In regard to any organisms and their germs which 
it might contain, he says:—‘“It is necessary to 
maintain the elevated temperature (212° F.) for 
about five minutes to ensure complete destruction of 
their vitality.” 
Dr (afterwards Sir) William Roberts! mentions 
healthy and diabetic urine as being amongst the 
easiest fluids to sterilise, ‘‘three or four minutes’ 
boiling” sufficing, as he says, to bring about this 
result and cause the liquid to remain permanently 
barren, when kept at temperatures ranging between 
60 and go F. 
Professor Tyndall? also, in 1875, found five 
minutes’ boiling invariably sufficient to  sterilise 
urine when it was subsequently exposed to a 
‘““moteless air.” 
This unanimity as to the barrenness of urine after 
a brief boiling in its acid state, together with the 
fact that, like other fluids, its fermentability was 
found to be increased after neutralisation by potash, 
seemed, as | have said, to make it a fluid specially 
favourable for trials as to the cause of the increased 
fermentability. Two alternative views were, of 
course, possible as to the cause of the fact in 
question—(1) It might be due to the “survival of 
germs” of some of the ferment-organisms in the 
boiled neutral infusions, as Pasteur assumed ; or (2) 
it might be due to the mere chemical influence of 
potash in initiating and favouring the molecular 
I“ Phil, Trans,” vol. clay. pt. 2, p41, 
# Phil. Trans.” 1676, vol. clxvi. pt: 1,.-p. 42, 
