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Scientific Memoirs by
With regard to this latter case, however, I must here draw attention to
three points. In the first place it must be allowed that the failure to detect
commas in the cultivation does not absolutely prove their actual absence from
it . This is due to the well-known fact that colonies of commas and other
schizomycete organisms cultivated on agar-agar jelly fail to present the same
constant, well-defined, specific macroscopic characters which they possess in
common gelatine cultivations; so that, although it is in most cases possible to
determine readily that certain colonies are not composed of commas, it is at
the same time impossible macroscopically to distinguish those that are com-
posed of commas from colonies belonging to certain other forms. This being so,
it follows that where commatous colonies are only present in small numbers in a
mixed cultivation, they may fail to be detected unless specimens from every
individual colony present be examined. Now in the present instance this course
was not followed; but, on the contrary, only a very limited number of colonies
were examined due to the cultivation having been carried out at a time when a
press of other work was in hand. In the third place, believing as I do in the
polymorphic nature of the commas associated with cholera, I do not feel con
-vinced that in any case such as this, where only a single primary cultivation was
conducted, the mere absence of recognisable commas satisfactorily demon
-strates the absence of the organism. Unless a succession of cultivations be
carried out under conditions favourable to the appearance of commas, it is
impossible to determine that any material, however free of actual commas, does
not contain potential ones—does not contain forms which under certain condi--
tions would be capable of becoming converted into or of giving origin to
commas. In the present case colonies of minute straight bacilli abounded in
the cultivation, and I do not think it impossible that these were developmentally
related to commas.
The facts in regard to the case in which it was distinctly ascertained that
the materials cultivated were really not of choleraic origin are the following. An
extensive series of cultivations of normal alvine materials had led to the conclu
- s i o n t h a t t h e c u r v e d s c h i z o m y c e t e o r g a n i s m s o c c u r r i n g i n t h e m , a l t h o u g h o f t e n
present in considerable numbers, were not reproduced in artificial cultivations in
neutral or alkaline agar-agar jelly, and that they therein differed from those
occurring in choleraic media. In order to obtain a sharply defined demonstra--
tion of the existence of this difference advantage was taken of the arrival of a
supply of material from the hospital derived from a case, admitted as one of
cholera, to start simultaneous plate cultivations of it and of a healthy alvine
evacuation containing appreciable numbers of commas, on alkaline agar-agar
jelly. On the following day both cultivations were carefully examined with the
confident expectation of finding colonies of commas present on the one plate.
and absent from the other. In place of this, in spite of the most careful and
extended examinations of colonies, no commas could be detected in either
cultivation. There could be no doubt as to the presence of curved schizomy-