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Scientific Memoirs by
was composed of short, thick, highly curved commas, resembling those developed
by the same form in non-neutralised agar-agar media, and in that of θ of
abortive commas and cocci. The elements in cultivations of λ are very similar to
those present in non-neutralised agar-agar media, and those in δ are much more
highly curved than they ordinarily are in any artificial medium, and present all
the characters of those which were present in the initial plate culture of the form
and which are figured in the photograph illustrating them in my previous paper.
The various forms of choleraic comma-bacilli occurring in Calcutta thus
continue persistently to show distinctive peculiarities in spite of prolonged
exposure to like conditions of environment, and it remains now to endeavour
to obtain a clear idea of what these are. This will be facilitated by a brief
summary of the essential features presented by the growths of each individual
form in the several media ordinarily employed in cultivations.
Form α.
I. Growth in neutralised agar-agar media.—Occurs both in the substance and on
the surface of the medium ; growth on the surface, conspicuously retarded by concentra-
tion of the medium or depression of temperature, always very smooth and polished and
quite devoid of any but the faintest traces of adhesiveness. The elements of considerable
size, blunt, only slightly curved and highly aggregant. (Plate IV, Fig. I.)
2. Growth in non-neutralised agar-agar media.—Relatively rapid but confined to the
surface ; elements generally somewhat shorter than those in neutralised media, but other-
wise retaining the same characters as they show there.
3. Growth in common gelatine media. —Liquefaction occurring much more rapidly
than in cultivations of any other form and accompanied by relatively limited multipli-
cation of the elements of the growth; the channel of liquefaction very rapidly assuming a
cylindrical form, extremely transparent and finely dotted. (Plate I, Fig. I, a . Plate II, a,
Figs. I-8 a .)
4. Growth on potatoes. —Generally entirely absent or of a purely abortive character ;
when most vigorous occurring in the form of very thin brownish expansions consisting of
elements resembling those in common agar-agar media mingled with others of larger size
more or less involuted and embedded in a gelatinous, adhesive basis ; in certain cases
local thickenings occur projecting from the general surface of the growth, and containing
accumulations of similar constituents.
5. Growth in bouillon. —General clouding of the fluid and formation of a surface
pellicle occurring rapidly ; abundant evolution of cholera-purple on the addition of acids
followed by rapid subsidence of deposit and complete clearing ; growth entirely absent in
non-neutralised bouillon.
Form β.
I. Growth in neutralised agar-agar media. —Occurring rapidly both interstitially and
superficially, growth on the surface not retarded by condensation of the medium or by
depression of temperature as that of form a is ; normally rough and sometimes con-
spicuously so ; constantly wanting in adhesiveness ; elements quite unlike those in form
a, being much shorter, relatively thicker and better curved and having no special ten-
dency to aggregation. (Plate IV, Fig. 2.)