Medical Officers of the Army of India.
The elements of this species are morphologically very distinct from those
of the previous one. They are not by any means so constant in respect to size
as the latter are, but are almost always considerably smaller than they are
They may be described as typical Commas, being short, thick, well-curved, and,
as a rule, with pointed extremities (vide Plate I, Fig. 2). They have no
special tendency to aggregation, and when introduced into fluids become readily
and evenly diffused throughout them. When examined in neutral salt-solution,
they are characterised by their excessively active, darting, and swarming move-
ments.
Their power of liquefying gelatine is conspicuously greater than that of the
previous species, and, indeed, seems on the whole to be higher than that of any
of the other species. The solution takes place with special activity at the sur-
- f a c e o f t h e m e d i u m , a n d h e n c e i n t u b e - c u l t i v a t i o n s t h e e n t i r e s u r f a c e b e c o m e s
liquid at a time when corresponding tubes of the previous species still show a
wide rim of solid gelatine around a limited crater. Due to the special rapidity
of the liquefaction at the surface, the liquefied area takes the form of a funnel
which tapers much more than that present in the case of cultivations of species a.
Gelatine plate-cultivations show corresponding distinctive features from those
of species a , the colonies growing more rapidly, and showing distinct evidences of
their liquefying newer relatively early.
The growth where Agar-agar replaces common gelatine in the basis is also
relatively rapid. Where the basis is neutral, or slightly alkaline, and is relatively
dense, the rapidity of growth, and specially of surface-growth, as compared with
that in species a is very conspicuous, and the surface-growth in tube-cultiva
- t i o n s o f s o m e d u r a t i o n i s e v i d e n t l y t h i c k e r t h a n i n i t . I t r e s e m b l e s t h e s u r f a c e
growth in tubes of species a in being either diffluent, or only very slightly
adhesive, but differs conspicuously from it in being almost invariably rough or
wrinkled and dryish (vide Table I). The colonies which develop in Agar-
agar plate-cultivations are larger than those of the former species of similar age,
and they are also less dense in texture, and have a greater tendency to become
confluent. When cultivated in non-neutralised Agar-agar basis, it grows much
more readily, especially at low temperatures, than species a , evident growth
usually showing itself within twenty-four hours, and proceeding with relative
rapidity to form a stratum of considerable thickness over the surface of the
medium. As in the previous case, there is no appreciable interstitial growth
along the track of the needle. The growth on potatoes is highly characteristic
and very distinct from the corresponding growth in species a. It takes place
comparatively readily, more especially when the growth employed as a source of
materials for inoculation is that in a cultivation on non-neutralised Agar-agar
medium. It is relatively thick, and of a yellow color, ranging from pure ochre
to pale primrose, or strong canary yellow, and in successful cases is of very
considerable thickness. It has in many cases a tendency (vide Plate II, Fig. 2)
C 2
II