370 ON THE LACTIC FERMENTATION 
infected water was added by means of the small syringe? (figured at p. 365) to 
each of five glasses of pure boiled milk. The result of this inoculation was 
that one only of the five glasses was affected at all. The contents of four 
remained permanently fluid and unchanged, and when examined with the 
microscope after the lapse of thirteen days, showed no bacteria of any kind. The 
milk of the fifth glass, however, was, in the course of the third day after inocula- 
tion, converted into a solid mass, and on examination was found to be sharply 
acid, and under the microscope there were seen among the granular masses of 
caseine countless motionless bacteria with the ordinary characters of Bacterium 
lactis, specimens of which were sketched and are reproduced in this diagram 
(Plate XIV, Fig. 9). No other bacteria, however, were to be discovered ; we 
had got rid of the moving species which was seen to be associated with it in 
the milk before dilution, and a fortiori it might be believed that other species, 
doubtless present in the original milk, but in too small numbers to be detected, 
had been avoided. 
Having therefore presumably obtained the Bacterium lactis pure and un- 
mixed, I proceeded to ascertain its behaviour in other media. I inoculated 
a glass of uncontaminated unboiled urine with it; and now, instead of either 
the moving bacterium which resulted from a corresponding inoculation with 
sour milk a few days before, or the large coiled organism of the experiments 
done four years previously, there appeared a motionless bacterium with identi- 
cally similar characters to those of the Bacterium lactis in the glass of milk, 
as will be seen from this diagram (Plate XIV, Fig. 10) made from a sketch taken 
two days after inoculation of the urine. Had either of the forms seen in the 
previous experiments been present, the insignificant motionless Bactertum lactis 
would probably have escaped notice altogether. In the course of the first 
twenty-four hours its growth was indicated by delicate white vertical streaks 
on the glass without any turbidity of the liquid. Next day, however, the fluid 
was decidedly nebulous, but after that period the growth was exceedingly slow, 
and very little effect was produced upon the urine as regards either odour or 
reaction. Nevertheless it still retained its power of acting as a lactic ferment 
when introduced into milk even after four days’ residence in the urine; for 
having inoculated at this period eight glasses of boiled milk with drops of the 
urine diluted with enough boiled water to provide about three bacteria on the 
average to each drop, all the glasses soured and curdled within three days.? 
On the day on which this fact was observed, and when the bacterium was 
* The nozzle of this syringe was purified by boiling it in water in the interval between its employ- 
ment referred to in the above note and the inoculation of the milk-glasses. 
* Even after seventeen days in the urine the organism still retained the power of causing lactic 
fermentation, though it was then not quite so energetic, requiring an additional day to produce curdling. 
