302 ON THE GERM THEORY OF PUTREFACTION 
of the corpuscles themselves, many of which are already of the spherical form. 
And the spherical cells, when examined with a high power, were found to be 
nucleated like those of the last scum. Here and there a plant was found in 
which, in consequence, I presume, of greater vigour, the filamentous growth 
had proceeded further before the corpuscular development occurred, and formed 
septate branches, reproducing exactly the original filamentous form of the 
organism. This is illustrated by d, which represents part of another plant, 
drawn under the high power in the evening of the same day, and introduced 
not only on account of the delicate septate branch which it presented, but 
because nucleated spherical cells were seen to spring directly from little stalks 
on the thicker portion. 
Next day I found one plant so beautifully illustrative of the whole subject 
that I took a sketch of it, which is represented at e, Plate X, the drawing being 
on a much smaller scale, to enable me to include the whole. The plant had 
sprung from a spore situated not far from the edge of the island, and had grown 
towards the air-chamber, and, arriving there, had continued to spread itself 
upon the under surface of the thin glass that formed the roof of the chamber. 
It will be observed that the part of the plant which is most distant from the 
air-chamber has assumed the zigzag form resulting from a tendency to break 
up into segments, and has produced a considerable number of spherical spores. 
Nearer to the air, again, the plant retains its original form, and has very few 
conidia ; while the part in the air-chamber presents the characters of a branched 
filamentous fungus entirely destitute of conidial formation, and this in the 
very same plant which in another part of its course has the loosely jointed 
character with spherical spores. 
But how were these differences in different parts of the plant to be ex- 
plained ? Why did the portion in the air-chamber retain the purely filamentous 
and compact character, while the part on the island and other plants situated 
there became broken up, and produced conidia? The conidial development 
upon the island could not be the result of deficiency of oxygen ; for this mode 
of growth occurred in greatest profusion in the scum of the urine-glass, which 
was freely exposed to air which was being constantly changed. And in point 
of fact, the air in the glass garden was not nearly exhausted at this period ; for 
on examining it again on the 3rd of October, I found that the filamentous form of 
the fungus had by that time grown rampantly over the roof of the air-chamber, 
and had even grown down its walls in some places, and spread upon its floor. 
The obvious explanation appeared to me to be, that the agent which exercised 
the modifying influence upon the growth of the organism was some volatile 
product of fermentation, probably that which assailed the nostrils with a pungent 
