328 A FURTHER CONTRIBUTION TO THE 
glass, had been exposed to a high temperature between metallic plates to diffuse 
the heat and avoid cracking, and cooled without access of dust. With heated 
forceps the covering glass was raised and, a minute drop of the Pasteur’s solution 
with its organism having been mingled with a large drop of urine on a glass 
plate purified by heat, a little of the mixture was placed on the island. The 
covering glass was then luted down with melted paraffin, applied with a hot 
steel pen after a drop of water, boiled and cooled under the protection of car- 
bolized cotton, had been placed in the ditch with the pipette to ensure a moist 
atmosphere. Immediately after this had been done I examined with the micro- 
scope and saw the minute bacteria of the Pasteur’s solution as shown at c, in 
the Plate, in active movement. On looking again five hours later I found 
those bacteria replaced by large ones as seen at d, still moving though the move- 
ment was now languid. Within this short time the one variety of the organism 
had been converted into the other. Even if we supposed that the thick ones 
were of a different kind and that one of them had been present originally in 
the garden unobserved by me, their large numbers at the end of five hours 
and the vanishing of the small ones would be equally inexplicable. Hence, 
I think, we may regard it as demonstrated that the minute bacteria of the 
Pasteur’s solution and the coarse ones of the urine were one and the same 
organism. 
Other more remarkable facts, however, remain to be recorded. On the morn- 
ing of the 22nd of August, wishing to ascertain whether this organism, after being 
so strangely modified in urine, in Pasteur’s solution, and then again in urine, 
retained the property of inducing the lactic-acid fermentation in milk, I intro- 
duced a minute drop of Urine No. II into a second glass of milk decanted at 
the same time as the former, and which we may designate Boiled Milk II. Nine 
hours later test-paper already indicated a slight degree of acidity, and bacteria 
were found, five or six in each field, about as thick as those in the urine of inocu- 
lation, and also pretty long, generally single, but sometimes double as shown 
ate, Plate XIII. On looking at the same slide four hours later I found that other 
bacteria, much more minute and showing active progressive or rotatory move- 
ments, were also to be seen, and next morning such minute and active ones 
were alone discernible in another drop taken for examination. The acid reaction 
was now more marked, and the acidity continued afterwards to increase, till 
within three days the milk had set into a solid mass. 
But along with the lactic-acid fermentation another and very different 
change took place in the milk during the first twenty-four hours. On first 
looking at the glass on the morning of the 23rd, twenty-one hours after inocu- 
lation, I was amazed to see at the bottom of the glass a deposit about a line in 
