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Scientific Memoirs by
choleraic bacilli as mere varieties of one and the same species, I do not
individually believe that this can fairly be done without striking at the root of all
attempts at classification of Schizomycete organisms, or, indeed, at classification
generally. They, no doubt, do present certain common morphological and
physiological properties, but this is not peculiar to them as a group of distinct
organisms. Were it not that groups of organisms constantly do so, it would be
impossible to have any classification beyond a mere category of individual species,
and if we are to adopt the view that the possession of certain common properties
indicates specific identity, then we have only to push it far enough, and there
is an end of classification altogether, and we must remain content to affirm
that all living beings, whether animal or vegetal, are mere atypical varieties
of a common primitive protoplast.
The resemblances which distinct forms of choleraic bacilli may under
certain circumstances present are certainly very conspicuous, but the conditions
under which these resemblances arise are not such as to justify us in regarding
the latter as indicative of specific identity. In a limited number of instances
we find resemblances manifesting themselves under the influence of like
conditions of environment, but this is almost always where the latter are
unfavourable and the growth correspondingly unhealthy, and more or less
abortive. Where this is not the case and resemblances yet are present, we do not
find them arising under the influence of like conditions, but under that of diverse
ones, and as the result of the fact that the different forms are differently
affected by the latter, certain features presenting themselves in one form
under given conditions and in another under totally distinct ones. Now, no one
will propose to ascribe any decisive value to the characters presented by abnor-
mal, unhealthy growths, and the resemblances which arise under the influence
of unlike conditions, in place of being any proof of specific identity, are
strong evidence against it. The constancy with which the different
choleraic comma-bacilli continue to present conspicuous differences whilst
exposed to certain like conditions, and the fact that the modifications
which they undergo on being transferred from one to another environment,
differ from one another so as to cause certain forms when in one environ-
ment to present resemblances to others in another environment render
it extremely improbable that they do not possess specific peculiarities. Even
where we find that organisms which, under the influence of particular
common conditions present conspicuous differences, cease to do so any longer
under the influence of other but equally common ones, we have no satisfactory
evidence of any essential identity in their nature unless the resemblance
between them has arisen as the result of truly assimilatory modification— unless
it has arisen as the result of a like action of the new common environment
upon them. Where it has arisen merely because one organism retains its
original characters unchanged, whilst the other becomes modified under thes