The sun. [volume] (New York [N.Y.]) 1833-1916, 1907-07-14


plexity. No one has any doubt in presence
If such widely differentiated types. The
dlffculty begins in forms having great
nilnities with each other, such as the horse
and asa, hare and rabbit, bulldog and poodle.
Among such ~nciahboring forms We hesi-
tate ami essay an estimate Of the differ
pncps which separate the two types. so as
TO rome To q reasonable conclusion. In
some cases the answer is disconcerting 20
people not prepared for it,. For example.
the horse and. ass are said 10 be Of different
species. while the Great Dane and the King
Charlesa are rankedin the same species dog.
IL il certain. however. that the descriptive
differences between the two dogs are far
more considerable than those which may be
detected between the horse and the ass.
A. bottom under all this question of
species there lies an error Of method For
"A very long time men had an idea that species
were entities created separately and existing
independent Of each other. In other words
It was ~believed'that there was some absolute
definition Of species. The belief persisted
even after the discovery Of the transforma-
ton OF species, and men still feel the need
Of cataloguing in strictly limited pigeon
holes all the highly variable bodies called
living beings Evidently such classifca-
ton Ia accounted useful for the narration of
facts and II is good enough for the purpose
when IL 10 clear n easy to handle. There
10 no necessity OF asking whether our cata-
logued p~igeonholes are separated by some
principle Of higher philosophy or some abso-
lutte definition Of species already existing
before men undertook to classify them
Yet even nowadays men AJAX what species
Ia. instead OF using their liberty to define the
groups in which for their own personal con-
venience they shut up all living being s
Cuvier's definition Of species il still currently
taught: THE collection of all the organized
beings descending from each other or from
common parents and Of those resembling
them as much as they resemble each other"
This manifestly is a definition after the
fact. and not a priori such as ought to be
made when we have a catalogued classifica-
ton in view In reality II is not a definition
at all. but a biological theorem and not
strictly true at that. II we dissect Cuvier's
proposition we find first our intuitive idea
Of beings Of the same species, then a theorem
that children are Of the same species as their
parents II il no less obvious that Cuvier's
vi IottOt NbO vIb btbAth III W.
is the denial Of transformism. II we accept
in It's strict sense the proposition children
are OF the same species as their parents"-we
shall have to reason step by step to the neces-
sary conclusion that the animals Of the pres
ent day are Of the same species as their re-
hottest ancestors Unluckily people do not
generally look 30 close in natural sciences.
and in almost all courses OF zoology pupils
are still taught transformism and Cuvier's
definition together.
To give absolute value to the idea of
species it would be needful that the groups
called species should be separated from
neighbori;g groups by finite. discontinue
ties, but il would also be needful that there
should exist perfect continuity among
the different individual types constituting
the species. As a matter of fact this is
not the case. The author of this book
demonstrates how inevitable it is that
finite differences should exist bel any
two living individuals. The existence OF
such differences is the condition of the
step from any being whatever to any other
being. Accordingly when there is a step
from one species to it's neighbor the dis
continuity will differ only in dimension
from that which separates two individuals
OF the same species
Under the circumstance the definition
OF species becomes merely a question OF APP
probation; IT, is no longer a strict and alb
solute definition. Before transformism,
indeed, belief in the possibility Of an abso-
lutte definition Of species was possible
and necessary. The step separating in
dividuals OF the same species might in
theory be passed over on the score of the
variations accompanying individual null
tiplication; but the discontinuities limiting
species were impsssable. This then was
the basis Of an absolute definition: the
variation resulting from adaptation and
reproduction could not step over the limits
of species. The species had therefore
to be defined after the fact. On the con-
trary. in the transformist theory. we are
obliged to define species a priori for con-
venieuce in classification. without preoc-
cupying ourselves with metaphysics.
II our author we're to undertake to define
species he would call it the sum total of
individuals among which only cumulative
differences exist. He recognizes. however,
that such a definition would be simply
conventional and wou need to be sup
plemen:od with other conventions. for
we no longer believe in essential qualities.
The fact is recalled that when De Vries
showed us sudden mutations produced
in Enothera. many scholars gravely dis
cussed the question whether the step passed
over was a limit Of species; whether,
strictly speaking. we ought to consider
the mutation TO have passed over the limits
Of the species. There might have been
sense in this before transformism, but
the definition Of species has no longer any
philosophical vnlue.
III.
The concluding chapter. which treats
Of the appearance Of life. begins with a
summary OF the previous considerations.
which suffice for understanding the phe-
nomenon OF the progressive evolution of