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The speaker thought that he personally meant by “a 
species” something like this—a group (the largest he could 
bring together) of forms so similar as to suggest descent from 
one ancestral pair of which they had retained practically all 
the heritable qualities: 7.e. they differed only in such respects 
as we have reason to think either (a) individual and not 
phyletic (aberrations, monstrosities), or (b) phyletic but quite 
trifling in comparison with the conformity in other points 
(races, sub-species), or (c) resulting from a potential variability 
which was itself part of the original inheritance (dimorphism, 
special adaptations, etc.). He believed that ‘‘syngamy” would 
practically always characterize such a group, but that it was 
not the character which he himself had most in mind when 
considering whether a group was or was not a species. Nor 
did he think the absence of links with other groups essential 
to the definition. 
Species seemed to him real but not permanent or ultimate 
phenomena in nature. At any time a transverse section 
through the “ Tree of Life” (Darwin) would show us forms 
arranged at actual differing distances from one another, 
but no two such sections taken at different epochs would give 
the same result. What is now a species will one day be 
represented by a genus, or it may have passed out of existence 
altogether. The Systema Nature seems to conceive Science as 
mapping out and measuring a stationary field, we have come 
rather to regard her as having to deal with a flowing river. 
Dr. F. A. Drxry said that though it was easy to define a 
“‘species”’ in the logical sense, the zoological conception of 
the term was surrounded by great difficulties. Darwin had 
explained what he meant by a species in contradistinction to 
a variety; but, as Professor Poulton pointed out in his 
Presidential Address, when asked for a definition by Phillips, 
Darwin had admitted his inability to give one. It was 
necessary to have a working unit for purposes of classification. 
Linneus had supplied such a unit which had served its 
purpose for a time, but like other attempts it had eventually 
been found wanting in correspondence with the facts of nature. 
The present state of fluidity, however, was more hopeful than 
the old confusion out of which the Linnzan conception 
