Medical Officers of the Army of India.
In feebly acid cultivations a certain, and sometimes a considerable, proportion of
typical commas was present associated with others of shorter, relatively thicker
form and in many instances containing vacuoles. In the larger specimens of
these abnormal commas, the characteristic curvature was still distinctly recog
-nisable, but these were connected by a series of insensibly gradated forms with
bodies which no longer showed any traces of curvature and which presented the
character of rounded or oval cocci with or without a distinct central vacuole.
Such bodies occurred either isolated or in pairs, or in certain instances in con
-nected series of various numbers so as to give rise to rod-like bodies. The
second series of experiments yielded corresponding results. The transfer of
materials derived from pure cultivations of commas in alkaline or neutral media
to acid substrata resulted in the development of bodies modified as described
above in varying degree according to the character of the substrata as feebly or
strongly acid. Successive cultivations in strongly acid media resulted in the
development of crops almost entirely, or entirely consisting of the modified coc
-cal forms, and successive cultivations of materials of this nature in alkaline media
led to a gradual replacement of the coccal forms by commas and the ultimate
appearance of pure cultivations of typical commas. These results were repeated
with methodical and extreme regularity as to leave no reasonable ground to doubt
that they really indicated a considerable range of polymorphism as a character
of the choleraic commas, but the precise developmental relations of the various
forms to one another remained for some time a matter of obscurity.
At length, however, a set of cultivations presented itself which afforded
means for clearing up this question. This, as has already been mentioned, was
one in which the substratum was alkaline and in which peculiar abnormal forms,
similar to those described by Dr. Klein, formed a very conspicuous feature.
Dr. Klein's observations had clearly shown that the development of vacuolate
forms was a phenomenon appearing under the influence of certain conditions in
alkaline cultivations. According to his experience the condition which appeared
most closely related to it was depression of temperature. In those cases in
which it was observed in Calcutta it did not appear to be so much primarily
related to thermal conditions, for it occurred in some cases in cultivations con
-ducted during the height of the hot season, as to prolonged cultivation in one
medium. As a rule vacuolate forms were either absent or only present in very
limited numbers in specimens derived from recent neutral or alkaline cultivations,
and where they appeared conspicuously did so in cultivations of some duration
and in constantly increasing numbers as time advanced.
This was very distinctly the case in one cultivation. What rendered this
cultivation particularly instructive was, however, not so much the numbers in which
the vacuolated forms occurred as the exceptionally large size to which many
of them attained, which rendered it possible with comparative ease to follow out
the various modifications of form and to recognise the developmental relations
which the various forms bore to one another, Both the distinctly vacuolate
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