etl) 
Max Miiller’s special criticism falls to the ground, but his 
general exhortation remains, and I think we shall do well to 
be guided by it, and attempt to apply it to this difficult and 
elusive word SPECIES. 
The passage I have quoted was Darwin’s prediction of the 
meaning which would be attached to the word “species ”’ by 
the naturalist of the future. Nearly half-a-century has passed 
since those words were written. For more than a generation 
the central ideas of the “Origin” have been an essential part 
of the intellectual equipment, not only of every naturalist, but 
of every moderately intelligent man. What then is the 
meaning of the word “species” to-day, and how does it differ 
from that of the years before July 1, 1858, when the Darwin- 
Wallace conception of natural selection was first launched 
upon the world ? 
The present occasion is especially favourable for this inquiry, 
because we have just been given two additional volumes of 
the letters of Charles Darwin. After the three volumes 
published in 1887, naturalists were certainly unprepared for 
the welcome revelation of such a mine of wealth. The work 
is all the more valuable because it contains many letters from 
Alfred Russel Wallace and Sir Joseph Hooker, thus giving 
both sides of a part of their correspondence with Darwin. 
Then in 1900 the “ Life and Letters of Thomas Henry Huxley ”’ 
appeared, so that we are now admitted “ behind the veil,” and 
can read, as never before, the central thoughts of the great 
makers of biological history. On the publication of the last- 
named work, I took occasion to combat the view that the 
thousand closely-printed pages might have been reduced by 
omitting and condensing many of the letters. The serious 
student of those stirring years requires the opportunity of 
thinking over and comparing all the available thoughts and 
opinions of the chief actors in the memorable scene ; and the 
very repetition of certain ideas, which proves their persistence 
and dominance in the writer’s mind, is a matter of deep 
importance and interest. However it may be to the general 
reader, the student would deprecate the omission or condensa- 
tion of any of the writings of Darwin or Huxley. ‘The special 
interest and value in the letters of these men depend on the 
