XVill THE EVOLUTION OF LIFE 
In the present volume I shall not deal at all with 
Heterogenesis. Five years of independent work 
have been recently devoted by me to this subject, 
and the results were published in my “ Studies in 
Heterogenesis ” (1901-1903); while portions of these 
results, together with my views on the subject of 
living matter generally, have been embodied in a 
more popular form in my recently published book on 
“The Nature and Origin of Living Matter.” 
Here we shall limit ourselves to the problems 
connected with Archebiosis—that is, to the question 
of the actual origin of life or the genesis of living 
matter. I shall, moreover, limit myself to a con- 
sideration of the evidence bearing upon this question 
which has accumulated since 1872, when my work, 
“The Beginnings of Life,” was published. An 
account of the earlier investigations on this subject, 
from the time of Spallanzani and Needham onwards, 
will there be found, which it would be comparatively 
useless to attempt to repeat ina much condensed form. 
It seems better to devote all available space to a fuller 
consideration of the more modern aspect of the 
problem and more recent experimental work—and, 
moreover, to take a broad outlook upon the question 
generally, in the light afforded by modern investiga- 
tions on the constitution of matter, on the “ mystery 
of radium,” and on “ inorganic evolution.” 
