170 THE EVOLUTION OF LIFE 
tion or inurine is decomposed at 100° C., and even 
at temperatures much lower. The product of de- 
composition is carbonate of ammonia.” What I had 
learned from Fownes, together with this statement, 
subsequently induced me to give special attention 
to the subject ; and the result has been the full con- 
firmation of Pasteur’s recent, in opposition to his 
earlier, impressions and statements. I doubt, indeed, 
whether even he was aware of anything like the extent 
to which such changes will go on in the incubator— 
and, as we have seen, they were absolutely unknown 
to Sir William Roberts and Professor Tyndall. The 
following paragraphs are reproduced from my 
memoir in the Journal of the Linnean Society (pp. 
38, 39) — 
“If a piece of moistened litmus paper is exposed 
to the steam coming through the capillary orifice of 
a retort in which ordinary acid urine is being boiled, 
this paper is for a time rendered faintly blue, show- 
ing that some ammonia is being given off, suffi- 
cient to make the steam from acid urine faintly 
alkaline.” 
“T then proceeded to make some quantitative 
determinations as to the amount of diminution of 
acidity occasioned by boiling urine both in an open 
vessel and, under pressure, in a closed vessel—also 
as to the subsequent rate of change when urine 
was kept at different incubating temperatures. Ac- 
cidents happened to some members of the first series 
which I prepared with the view of throwing light 
upon this subject. The results ascertained from 
