ON THE NATURE OF FERMENTATION 345 
fissiparous development, in a manner, however, differing from the transverse 
fissiparous multiplication of bacteria, in being crucial.’ But, besides the granu- 
ligera, there were among the contents of these test-tubes bacteria of different 
kinds, to judge by form and size, and in one of them was a toruloid organism, 
and in two others two species of filamentous fungi, one of which was of the most 
exquisite delicacy, though in general type of the same sort of arrangement as 
the common blue mould or the Ozdium lactis. The size of the filaments was so 
exceedingly small that twenty of them would lie abreast in a single human red 
corpuscle ; they were smaller in diameter than even the Bacteriwm lactis, smaller 
than the great majority of bacteria. I doubt if any such exquisitely delicate 
filamentous fungus has ever been seen before even by a professed botanist like 
my colleague Professor Bentley. But there was no Bacterium lactis, and there 
was no lactic-acid fermentation. 
What inference were we to draw? Was I to suppose that, although the 
lactic-acid ferment had been excluded, it was impossible to exclude others ; 
that others were present in the milk as it existed in the cow’s udder ; or was it 
that I had not been sufficiently careful ? The latter was the view I was disposed 
to take. The experiment had been performed in the cow-house, where certainly 
the air might be supposed to be reeking with organisms. I therefore per- 
formed the experiment a second time, and this time in the open air. It must 
be confessed it was not far from the cow-house, and it was a fine day at the very 
time of the year in which organisms most abound. On this occasion, I used 
twenty-four of the little covered test-tubes ; those which you see before you. 
The result was that this time, again, every glass had organisms developed in 
the milk which it contained. At the same time, every glass seems to be different 
from all the rest. Such fermentations as there are here, I venture to say, were 
never seen in milk before. I have brought before you a diagram, showing some 
of them on a large scale. I want particularly to direct your attention to these 
strange scarlet spots which occurred in almost all of them. They began as tiny 
scarlet dots, which spread as fermentative changes capable of self-multiplication 
in the substance of the milk. Here is one glass that is green, and here is another 
of an orange-yellow colour. Here are two that have two kinds of filamentous 
fungi. I have not examined them microscopically, but I shall very likely find 
there are some species that have not been described. 
I felt little doubt that these organisms had got in for want of sufficient care 
on my part. But how are we to explain these unheard-of appearances ? Simply 
thus. If the Bacterium lactis had been here, it would have taken the precedence 
of all other organisms in its development, and the changes which it would have 
* Vide Tvansactions of the Royal Society of Edinburgh, vol. xxvii, p. 319 (page 281 of this volume). 
