GERM THEORY OF FERMENTATIVE CHANGES 331 
to suppose that the two bacteria thus coexisting in the two fluids were both 
modified in form in the same manner by the two media, both becoming coarse 
and long-segmented in urine, and both minute and of ordinary bacteric aspect 
in the Pasteur’s solution ; for none of the minuter kind were seen in the former 
fluid, nor any of the coarser sort in the latter. Further, we should have to 
suppose that the ‘ pigment bacterium’, when introduced into milk, grew with 
ereat activity for twenty-four hours and then suddenly perished. For we have 
seen that no further deposit of pigment took place after the first night, although 
the milk remained fluid considerably longer, and on microscopic examination 
of a drop from the upper part of the glass next day, when granular masses of 
caseine showed that coagulation had begun, I discovered not a vestige of pigment 
in it. And in further proof that the pigment bacterium, supposing such a 
separate organism to have been present, had died, I found that a bit of the curd 
introduced from this glass at the close of the third day into another glass of 
the same boiled milk, gave rise to the lactic-acid fermentation, pure and simple, 
with no formation of pigment, and none of the putrid odour that had attended 
the pigmentary formation in the other glass. It may, perhaps, be suggested 
that the ‘pigment bacterium’ was poisoned thus early by the lactic acid 
generated under the influence of the other (supposed) organism. But unfor- 
tunately for such a view, we find the same transient character of the pigmentary 
function in urine asin milk. For, as has been before mentioned, the day after the 
inoculation of Botled Milk No. II from Urine ITI (resulting in the pigmentary 
fermentation), I introduced a drop from Urine IJ into another glass of the same 
urine with the result of reproducing in great beauty the long unjointed form 
of the bacterium. After two days more I inoculated from this Urine No. III 
a fourth glass of the boiled milk, in the hope of getting back the pigmentary 
formation. But no such thing occurred, merely the lactic-acid fermentation. 
Now it is scarcely conceivable that the ‘ pigment bacterium’ (supposing it 
present) should have perished so quickly in the urine as well as in the milk. 
For it is to be remarked that the urine was but little changed by the bacteric 
development that followed the inoculation, retaining its acidity at the close 
of the two days, while little effect was produced upon its odour. Besides this 
it must be borne in mind that, if the supposed ‘ pigment bacterium’ was derived 
from the original stock of sour milk, it had before survived a residence for three 
days in urine, which was the fluid originally inoculated. 
On the other hand, if we admit that there was only one organism present, 
but modified in function as in form by the different media, the course of events 
is exactly what we might have anticipated. It was in the Pasteur’s solution 
that the pigmentary function first manifested itself, not indeed during the first 
