330 A FURTHER CONTRIBUTION TO THE 
as I had never before seen in Pasteur’s solution. Next day this peculiar appear- 
ance was considerably increased, and on applying a pocket-lens, I discovered 
a number of minute dark brown specks disseminated over the glass, even close 
to the level of the liquid where the surface was vertical; each brown point 
having a tiny brown streak extending downwards from it. I succeeded in 
picking up one of these brown specks with the attenuated end of the pipette, 
and on examination found it made up of a mass of motionless bacteria of ordinary 
form, themselves colourless, but having sepia-coloured particles disseminated 
among them of the same tint and intensity of colour as the pigment from the 
milk, very irregular in form and varying in size from mere points, much smaller 
than the bacteria, to masses considerably larger, as is seen at u, Plate XII, 
showing that the pigment, though produced under the influence of the bacteria, 
as seems clearly indicated by its existing specially among the bacteric masses, 
yet was, as in the milk, a mere amorphous and unorganized product. Thus, 
we trace back the pigmentary function to the Pasteur’s solution, through the 
urine, although in the latter no pigment whatever was formed. This is in 
itself a point of interest, as indicating that the formation of pigment is not 
essential to the organism, but, just as in the case of the viscid substance pro- 
duced under the influence of Bactertum No. I, occurs only when the medium 
in which the bacterium is growing is of a nature fitted for furnishing the requisite 
materials. Further the knowledge that the organism which produced the 
pigment was present in the Pasteur’s solution and in the urine will aid us in 
considering the question whether that organism was or was not a different one 
from the lactic-acid ferment, and this we may now proceed to discuss. 
Supposing it to have been a separate organism, it is not at all likely that 
it found its way by accident into the first urine-glass or the Pasteur’s solution 
during the brief periods of exposure for inoculation or withdrawal of fluid for 
examination. For in no single instance have I known bacteria introduced 
before in this way. Nor can it have existed diffused through the original supply 
of milk, seeing that no pigment was produced in that stock or in the glass 
Boiled Milk No. I inoculated directly from it. We can only imagine it intro- 
duced from the original supply by supposing that it had entered the unboiled 
milk immediately before the inoculation of the first urine-glass, and was all 
taken up in the drop used for the purpose ; a contingency possible but not 
probable. 
3ut even if we admitted that, in spite of the slenderness of the chance of 
such an occurrence, a separate ‘ pigment bacterium’ had made its way acci- 
dentally into the first urine-glass or that of Pasteur’s solution, we should find 
ourselves confronted by a further series of improbabilities. We should have 
