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according to the nature of the substrata employed. If the initial cultivation be
conducted in an acid medium, we obtain a growth in which typical commas are
to a great extent replaced by vacuolate commas and cocci of various forms.If
material from such a cultivation be cultivated in alkaline or neutral media the
abnormal forms tend to disappear due to the development of typical commas
due to the ordinary processes of transverse division and to resolution and divi
- s i o n o f t h e v a c u o l a t e f o r m s . O n t h e o t h e r h a n d i f t h e s u b s t r a t a b e a c i d , t h e
commatous forms come more and more to be replaced by vacuolate and coccal
ones. This is due to the fact that under such conditions, whilst processes of.
vacuolation and of division of protoplasm continue to occur, the secondary
protoplasts have less and less tendency to assume the characters of commas and
more to repeat those of the parent cocci.
Vacuolate cocci or short commas, in which the process has advanced so
far as to lead to division of the protoplasm into two distinct polar bodies, will, if
placed under certain circumstances, give origin to pairs of commas, and if placed
under other conditions to pairs of cocci. Where the conditions are such as to
favour growth of a coccal type, the resulting cocci may either separate from
one another or may remain united in pairs or linear series. When they remain
united a series of forms arises which constitute a parallel to the vibrionic forms
which appear under certain conditions in growths of the commatous type.
Such are the conclusions at which I have arrived from
o b s e r v a t i o n e x -
periments of the nature described above. Should they prove to be well grounded,
they will only afford another proof of the absolute necessity of cultivations
carried on under distinctly defined conditions in order to any satisfactory deter
mination of the question of the presence or absence of schizomycetes of parti
cular nature in any suspected material.
A few special points still remain to be considered. The first of these
relates to the macroscopic features presented by cultivations of the choleraic
commas in agar-agar jelly. These are not at all of the specific and distinctive
type described as characteristic of cultivations carried out in common gelatine
media. There is in no case, so far as I have observed, any tendency to lique
-faction of the basis in the neighbourhood of the colonies. In plate cultivations
the latter are usually evenly rounded, sharply defined and of considerable size;
sometimes they present a slightly lichenoid appearance. In many cases they
attain a diameter of several millimeters. In one case such defined, colonies
were replaced by a general diffused haze pervading large areas of the plate.
In many cases the colonies are absolutely indistinguishable macroscopically
from those belonging to other forms of schizomycetes with which they are asso
-ciated. Like many other colonies ' composed of rod-like units they present a
peculiar bluish tint when the plate is held obliquely so as to subject them to a
certain amount of transmitted light, whilst the majority of colonies of coccal
origin under similar circumstances usually show a pinkish, yellowish, or whitish
color.