JuLy 16, 1897. ] 
something which does not vary. Perman- 
ent as an adjective means lasting and en- 
during, and thus it is contrasted with the 
adjective sense of the term variable. Thus 
when Darwin speaks of natural selection as 
acting by the ‘ preservation and accumula- 
tion of variations,’ there is nothing variable 
in that which is conceived of as being pre- 
served and accumulated. It is a character 
or morphological structure which is pre- 
served and accumulated in the offspring 
only when it is the same character which 
appeared in the parent form. It is the fact 
of the reappearance of the same character 
in the offspring which is meant by its preser- 
vation. It will be seen, thus, that the 
origin, or arrival into the organic struc- 
ture, of the particular concrete variation 
which, in any particular case, is trans- 
mitted and preserved must necessarily 
have taken place before natural selection 
acts in that particular case. Therefore, 
the variation, as an act, or the actual be- 
‘coming different, is of a two-fold nature : 
(1) It consists, first, of the growth of some 
part of the structure of the organism in 
some way and degree differently from the 
growth of the same part in the ancestor; 
and (2), secondly, there is the reproduc- 
tion of that difference in the offspring in 
accordance with the growth as it took place 
in the parent or immediate ancestor. Here, 
in the act, we see again a confusion of two 
acts, one of which is permanent and the 
other variable. The first act is a diversion 
or contradiction of the law of heredity, the 
second act is in conformity with it. The 
true variation, as an act, is thus a real de-_ 
parture, or diversion, from the phenomena 
of hereditary repetition. It is this which I 
understand Darwin assumed to have been 
spontaneous or constantly occurring, and 
it is the operation of natural selection, 
chiefly, and of other agencies working upon 
the living organisms, which, according to 
Darwin, results in the increasing diversity 
SCIENCE. 
83 
of the individuals. We are thus led by an 
analysis of Darwin’s own theory to find 
that the real variations occur prior to any 
of those operations of the organism, or of 
the environment, commonly supposed to 
have caused them. 
Darwin’s theory, nevertheless, is readily 
adjusted to the conception of the funda- 
mental nature of organic variation here 
proposed. It requires but an expansion of 
the idea of mutability of species so as to in- 
elude mutability of the individual and of 
organic matter itself. Natural selection is 
constantly producing heredity, not varia- 
tion. But natural selection is not the only 
cause ; environment in general, and we 
might extend the idea of environment and 
say that experience is constantly resulting 
in the hereditary transmission of qualities 
or characteristics from parent to offspring. 
The definite laws of heredity for any 
particular organism at any particular point 
in its history are but the recapitulation of 
the experience of its ancestors in overcom- 
ing, conquering and using for their enrich- 
_ment the impediments and constantly acting 
hindrances to their living and existence. 
Varying is the first, as itis the last, per- 
formance of the living being. Invariabil- 
ity is the law of the inorganic world, but 
is the sign of death among organisms. This 
thought was aptly expressed by the late 
James D. Dana, in the last revision of his 
‘Manual of Geology.’ Speaking of variation 
among organisms he wrote: ‘It is per- 
ceived that the law of nature here exempli- 
fied is not ‘ like produces like,’ but like with 
an increment or some addition to the varia- 
tion. Consequently, the law of nature, as 
regards the kingdoms of life is not perma- 
nence, but change, evolution ”’ (p. 1033). 
A rational and consistent conception of 
organic evolution arises from this theory of 
the fundamental nature of variation in 
organisms. Evolution is, to this theory, 
only the extension of the phenomena of 
