Medical Officers of the Army of India.
9
cases distinctly proportional to the vigour of the growth on the new medium.
For example, in my previous paper I pointed out that the vigorous growths of
species β, which I then obtained on potatoes, were characterised by their thick-
ness, their bright yellow colour and the almost micrococcoid elements of which
they were composed. The original series of cultivations died out during my
absence in Europe in the summer of 1891, and it was only after a very large
number of futile attempts at transfer from the now long-continued and thorough-
ly acclimatised series of agar-agar tube-cultures that any renewed growth on
potatoes was obtained. Long-continued cultivation on agar-agar media in the
case of most choleraic comma-bacilli is accompanied by very great diminution
or apparent absolute abolition of capacity for growth under the conditions pro-
vided by potato-cultures. In the present instance successful cultivations were
ultimately established, but these have never hitherto attained to the vigour of
the primary ones. The growth has been slow and relatively abortive, the colour
has never been of the original purity, and brilliance and the departure in form
of the constituent elements from that of those in the agar-agar cultivations has
never been nearly so great as it was in the primary series of cultivations, for,
though they have in great degree lost their characteristic curvature, they have
always retained a distinctly bacillar form.
Similar phenomena manifest themselves very conspicuously in the case of
another and totally distinct form of choleraic comma which was obtained
during the course of the past year. In this case the growth on potatoes has a
strong pink in place of a yellow colour (Plate IV, Fig. II, a). In cases in which
it is most vigorous it is of very firm, relatively dry consistence, and consists of
elements bearing not the slightest morphological resemblance to those in normal
continuous agar-agar cultivations, but which have assumed the form of very minute
diplococcoid rods, and which when en masse and viewed from their extremities
closely simulate micrococci (Plate IV, Fig. II, b). Where, however, the growth
is less vigorous, it becomes thin and moist without necessarily showing any
appreciable loss of colour but consisting of elements which tend more and more
to lose their diplococcoid character and assume the character of continuous
straight or curved rods, which in some cases are still evidently composed of
paired elements, but in others have more or less completely assumed the
characters of typical straight or curved bacilli. Where the growth is of purely
diplococcoid character transfer to an agar-agar medium may or may not be at
once attended by a resumption of the characters proper to normal, continuous
cultivations in it. In many cases the freest superficial and interstitial growth
may ensue in tube-cultivations in the medium without any tendency to immediate
resumption of the comma-form, whilst the latter is immediately resumed in the
case of plate-cultivations whether these be directly inoculated from potatoes
or mediately through the intervention of tube-cultures derived from them. In
most cases we have not merely this evidence of morphological modification, but C