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Scientific Memoirs by
2. Growth in non-neutralised agar-agar media.—Exceedingly retarded, and, in cases
where the medium is of dense consistence, not unfrequently entirely suppressed ; elements
consisting of large cocci, solitary or associated in pairs so as to form figure-of-eight bodies,
(Plate IV, Fig. 6.)
3. Growth in common gelatine.—When first obtained the liquefaction of the medium
was greatly retarded, but is now constantly more rapid than in the case of cultivations of
any other form save a; channel of liquefaction more or less cylindrical throughout; and
at the orifice containing dense flocculi or an actual solid plug ; the deeper portions of the
channel translucent, but not so transparent as those in the case of α, a very large deposit
invariably accumulating at the bottom. (Plate I, Fig. 4, b . Plate III, a, Fig. ι .)
4. Growth on potatoes.—Vigorous growths occurring rarely, but, whenever present,
invariably presenting precisely similar characters ; no evidence of any loss of capacity for
growth in connection with prolonged culture in agar-agar media ; forming a thin, somewhat
uneven, extremely polished and shining stratum unattended by any conspicuous discolour-
ation of the surrounding surface of the potato ; colour at first pale yellow, becoming gra-
dually warm Indian yellow, and then bright burnt-sienna ; elements in the form of thick,
fairly well-curved commas. (Plate IV, Figs. 8, a and b .)
5. Growth in bouillon.—Retarded; clouding occurring slowly and relatively feebly ;
no complete pellicle ever covering the surface, but a conspicuous collar or ring of dense
white material gradually forming around the edges ; the consistence of the ring very friable
and dense, so that on the slightest agitation it tends to break up into flocculi, which at
once sink to the bottom of the fluid and ultimately form a conspicuous deposit there ; capa-
city for giving rise to cholera-purple originally very feeble, but now highly developed ; the
addition of acids followed by ascent of the deposit to the surface in the form of large
dense masses of flocculi ; incapable of growth on non-neutralised media.
Form K.
1. Growth in neutralised agar-agar media. — O c c u r r i n g r a p i d l y b o t h o n t h e s u r f a c e
and throughout the substance; the superficial growth forming a thick stratum, usually
smooth and almost invariably highly tenacious or ropey in consistence ; elements liable to
vary greatly in form, but usually more or less resembling those of forms α or γ.
2. Growth in non-neutralised agar-agar media.—Relatively rapid but purely super-
ficial ; elements consisting of short, thick well-curved commas like those of form β in
neutralised agar-agar media.
3. Growth in gelatine. — P r o c e s s o f s o l u t i o n o c c u r r i n g c o m p a r a t i v e l y s l o w l y ; c h a n n e l
of liquefaction very opaque and containing a very large quantity of deposit. (Plate I, Fig.
5, a . Plate III, a , Figs. K .)
4. Growth on potatoes. —Has never been obtained in spite of numerous attempted
cultivations.
5. Growth in bouillon. —Presenting no characteristic features in neutralised media ;
entirely absent in non-neutralised ones.
Form λ.*
1. Growth in neutralised agar-agar media.—Occurring rapidly both on the surface
and throughout the medium ; surface-growth forming a thick, perfectly smooth, chalky
* This form certainly does not occur frequently in connection with cases of cholera in Calcutta. It
appears not improbable, however, that it may be more prevalent in certain other localities as it was obtained
in Nagpur by my friend Dr. Gerald Bomford in one of a small number of cultivations derived from cases
of the disease which occurred there in the course of 1 89o.