4
Scientific Memoirs by
tions were mounted from colonies, the appearance of which was most suggestive
and one of them was found to consist of commas of large size.
Another plate was inoculated four days after the introduction of the commas
into the water, and on this occasion only one dip of the needle was employed.
Two days later the cultivation contained a very limited number of concrete
colonies of bluish and yellowish tint.1 T w e l v e p r e p a r a t i o n s w e r e m o u n t e d , b u t i n
none of them was there anything even suggestive of commas.
Six days after contamination of the water another plate was set, this time
with o 5 C.C. On the following day the cultivation showed only a very few con
-crete colonies and two diffused patches. It was quite devoid of any perceptible
smell. Eleven preparations were mounted but in none of them were commas
present.
EXPERIMENT IV.—A litre and 100 C.C. of water from the same foul tank were
introduced into a clean, plugged flask and boiled strongly for periods of half an hour
on three successive days. Twenty-four hours later a plate was inoculated with 1
C.C. of the water. On the following day only three or four small colonies were
present, and, as these all consisted of a merismopædic form of Micrococcus which
at that time was excessively abundant in the air of the laboratory, it appeared
probable that the growth was due to local atmospheric contamination, and not to
the persistent vitality of any of the schizomycetes originally present in the
water. The latter was now inoculated with 1 C.C. of salt solution, crowded with
commas from a tube-cultivation of seventy-two hours' growth. The flask was
well shaken up, and after an interval of an hour 1. C.C. of water was used to
inoculate a plate-cultivation. On the following day the plate showed an even
diffusion of innumerable small bluish colonies. Three preparations were mount
-ed, and were all found to consist of pure cultivations of characteristic commas.
Two days later the plate was again examined. The colonies of commas had
increased greatly in size, and the cultivation had a strong characteristic chole
-raic smell.
Three days after the inoculation of the water a second plate-cultivation,
containing 1 C.C. of water, was set. On the following day this had a characteris
- t i c c h o l e r a i c o d o u r a n d w a s a b s o l u t e l y c r o w d e d w i t h s m a l l c o l o n i e s o f t y p i c a l
commas. The cultivation was almost a pure one, only one or two large concrete,
yellowish colonies, composed of other schizomycetes being present.
Five days after the beginning of the experiment another plate was in
- o c u l a t e d b y t h e f l u i d t r a n s f e r r e d b y o n e d i p o f a n e e d l e , a s t h e a m o u n t o f
commas indicated by the previous experiment was still so considerable as to
be likely to lead to overcrowding of the gelatine if large quantities of water
were used in inoculation. Only three or four colonies had developed in this
cultivation after twenty-four hours, and only one of these presented any features
suggestive of a colony of commas. A preparation was mounted from this,
and a second from one of the other colonies.In neither were commas present.
1 T h e c u l t i v a t i o n w a s a l m o s t o d o u r l e s s .