ORIGIN OF LIFE. 67 
in fact, would’ bea mockery of science. Assumed 
invisible germs, therefore, if postulated at all by the 
man of science, must be postulated to exist with 
properties similar to those of known germs, since 
they would all alike be composed of protoplasm, or 
simplest living matter. And; again, if he has satis- 
fied himself that, in all known: instances where trial 
has been made, the sudden exposure of living matter 
to a moist heat of 140° F. has proved destructive 
to it—that is, has destroyed the combination of 
attributes which previously entitled it to be called 
‘living ’—he can only conclude that this is a general 
truth which he may take for granted in the future. 
Being, from the Evolutionist’s point of view, alto- 
gether a question of physical or molecular property, 
the resistance of protoplasm or living matter to heat 
stands upon the same level as that of the degree of 
heat necessary to destroy or ‘kill’ one of the simpler ‘ 
chemical compounds ; or the degree of heat necessary 
to cause ebullition in a given fluid. These are all 
cases in which, as Mr. Mill said,* “we reckon with 
the most unfailing confidence upon uniformity,” so 
that “when a chemist announces the existence of 
a newly-discovered substance, if we confide in his 
accuracy, we feel assured that the conclusions he 
has arrived at will hold universally, though the 
* System of Logic, 6th edit., vol. i, p. 351. 
F 2 
