Medical Officers of the Army of India.
at first, regained it as they increased in age. The aërobic and anaërobic varieties,
when cultivated in Agar-agar, present certain distinct differences in form, the
former consisting of straight or only very slightly curved rods, whilst the latter is
composed of well-formed commas, and in those cases where anaërobic property
is only gradually regained as the result of repeated transfers from one Agar-agar
medium to another, corresponding gradual modifications in the form of the
elements are readily traceable. The presence of profound temporary alterations
in the constitution of the elements under such circumstances is indicated not
only by the differences in form and habit which have just been described, but
further by the fact that the purely aërobic variety when grown in broth does
not lead to those decompositions in the medium to which the development of
purple on the addition of acids are due. Both varieties grow readily in broth,
but it is only in cultivations of the anaërobic variety that any appreciable
d e v e l o p - m e n t o f p u r p l e f o l l o w s t h e a d d i t i o n o f a c i d s , a n d t h e e x t e n t t o w h i c h d e v e l o p -
ment does occur appears to be directly related to the degree of anaërobism
which is present. This frequently comes out most distinctly in cases where a
series of broth cultivations are made parallel to a series of successive Agar-agar
cultivations in which a gradual recovery of anaërobic property is occurring. In
the first broth cultivation there may be a complete absence of the constituents
requisite to give the color re-action, whilst in the subsequent ones, derived from
tubes showing progressive increase in anaërobic property, a progressive increase
in the degree of the re-action manifests itself. Similar phenomena present them-
selves in the case of broth-cultivations derived directly from the growths on
potatoes. Where the latter give rise to purely aerobic cultivations, in Agar-agar
media they give rise to cultivations in broth which fail to give the color re-action;
and just in proportion to their power of giving origin to anaerobic growths in the
one case is their power for giving rise to growths associated with varying degrees
of the color re-action in the other.
Cultivations in broth show no very distinctive peculiarities (vide Table
II). The formation of a pellicle on the surface is frequently somewhat re-
tarded. The fluid within twenty-four hours when exposed to temperatures of from
35° to 37°C. gives strong purple on treatment with acids. Cultivations of only
twenty-four hours hardly ever clear completely within twenty-four hours after the
addition of acids, and those of longer duration often remain persistently clouded.
This species is principally distinguished by the following characters : —
I. The morphological features of the elements.
2. By its minor power of liquefying gelatine, and sby the form which the liquefied
area in the medium presents in its earlier stages.
3.
By the very distinct features presented by the growths which it gives rise to
when cultivated on potatoes.
4.
VI.—SPECIES ξ .
This, as has been already mentioned, was derived from the same case and
the same evacuation as the preceding species.
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