
OF PUTREFACTION AND OTHER FERMENTATIVE CHANGES. 317 
not at all surprised to find, in the course of a few days, that the two glasses 
which had remained clear longer than the rest also exhibited organisms of 
different kinds, into the details of which I need not enter further than to say 
that those of one of the glasses included distinct bacteria. 
This experiment, rude as it was, showed clearly that exposure to the air 
might lead to the development of bacteria, provided always that the urine was 
free from contamination to begin with. And, further, the comparative slowness 
of any change in the two glasses which were neither treated with water nor 
intentionally exposed to dust, led me to think that in all probability, if the 
experiment had been performed more rigorously, I should have had no develop- 
ment at all in them; or, in other words, that the method of obtaining uncon- 
taminated urine was really trustworthy. If so, the fact was not only valuable 
as affording a ready means of performing experiments on the question at issue, 
but also exceedingly interesting in itself, as a strong corroboration of the view 
that the healthy living tissues prevent the development of these organisms. 
Accordingly, it seemed worth while to perform another similar experiment 
somewhat more rigorously, and this was done on the 21st November of the same 
year. Wine-glasses were “heated” as before, but each was provided with a 
separate cover, which was also “heated.” Two of these covers were inverted 
porcelain evaporating dishes, which had the advantage of preventing the direct 
effect of lateral currents of air; but as I had only two such dishes at hand, I 
used for the rest of the glasses square pieces of glass plate, overlapping well in 
all directions ; and a glass shade was put over all as an additional protection 
from dust. Further, instead of having the urine passed directly into the several 
glasses in succession, which was an inconvenient procedure, I had it introduced, 
in the first instance, into a flask provided with a porcelain cap, the flask having 
been heated over a red fire and allowed to cool under protection of the cap, 
which had also been thoroughly heated. The glasses were then successively 
charged from the flask with as little exposure as possible. The residual urine 
in the flask was boiled for nine minutes, and two additional ‘“ heated” and 
covered glasses were charged with the boiled urine, and to one of these a drop 
of tap water was added. I shall speak of those again by and by. As regards 
those charged with the unboiled urine, one was exposed for forty minutes to 
the air of the room ; one was exposed for nine and a-half hours ; and the other 
two (those with the porcelain covers), were, in the first instance, not exposed at 
all. The one exposed for nine and a-half hours to the air, showed, in four days, 
besides some minute plants of filamentous fungi, opaque spots in the cloud of 
mucous deposit, and next day the liquid was turbid with perfectly character- 
istic and abundant bacteria, and had acquired a rank, strong odour. The urine 
exposed for forty minutes showed indeed no bacteria, nor any torule or other 
organisms except three plants of filamentous fungi, which appeared to be of 
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