Medical Officers of the Army of India.
9
tionally small number of them. The figures corresponding to it are those of
No. 9 in the above series, and are greatly in excess of those in Nos. 10 and 11,
corresponding with samples of milk in regard to which no special precautions
had been taken, and which underwent the normal and rapid change in reaction
and coagulation. It was, however, a pure cultivation of one only of the species
of schizomycetes commonly present in milk. In cases where successive culti
- vations of one and the same sample of milk were made at different periods sub
- s e q u e n t t o p r o c u r a l t h e r e w a s a m p l e e v i d e n c e t h a t , f o r s o m e t i m e , a v e r y r a p i d
multiplication of schizomycetes took place, the successive cultures showing
progressive increase in the numbers of colonies which developed in them. A
rapid multiplication of schizomycetes thus occurs during the period in which
the milk is becoming acid and coagulating, but all the species normally present
in common specimens of milk do not appear to be equally active in producing
these changes. The exceptional sample of milk ultimately became acid in re
- action, but, even after an interval of 96 hours, was only feebly so, and only co
- agulated on being heated, although it was at the same time crowded with speci
- m e n s o f o n e o f t h e c o m m o n l a c t e a l o r g a n i s m s . A s s p e c i m e n s o f s t e r i l i s e d
milk inoculated with what seemed to be a pure cultivation of the same organism
in other cases showed coagulation within 24 hours, although with only transitory
acidity, it is a little difficult to account for the great delay manifesting itself in
this particnlar instance.
There was on the whole a remarkable uniformity throughout the entire
series of specimens in regard to the nature of the schizomycetes which they
contained. In regard to those which gave rise to definite colonies, two forms were
characterised by the extreme regularity with which they made their appearance
in the cultivations, one of them having occurred in 21 of the entire series of 24
cultivations and in 17 of the 20 samples of milk, and the other in 19 of the 24
cultivations and in 16 of the 20s a m p l e s . T h e f i r s t c o n s i s t s o f a l a r g e s p e c i e s o f
Micrococcus and was that which was alone present in the specimen of milk, in
regard to which special precautions against contamination were taken at the
time when it was obtained. The other was a very short Bacillus, the extremi
-ties of the rods being rounded so as to cause them to assume an oval form, and
there being a great tendency for association of the rods in pairs. The species
occurring next in order of frequency was another species of Bacillus distin
- g u i s h e d f r o m t h e p r e v i o u s o n e b y t h e g r e a t e r l e n g t h a n d r e l a t i v e s l e n d e r n e s s
of its rods. It was present in 11 cultivations derived from 10 distinct samples
of milk. A certain amount of Bacillus subtilis was recognised in nine cultivations,
derived from as many distinct samples of milk. In only one case were definite
colonies of it present in all the others it appeared to be present in the form of
diffused films spread out over the surface of the plate, and often so thin
as to escape notice entirely until the presence of rods contaminating
specimens derived from colonies of the other schizomycetes served to