
OF PUTREFACTION AND OTHER FERMENTATIVE CHANGES. 339 
greater vigour, the filamentous growth had proceeded further before the cor- 
puscular 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 XX VL. 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 zig-zag 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 2? 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 3d 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 stink, and that, where it was evolved in a limited space confined 
between the two plates of glass, it accumulated and produced its effect upon 
the plants. When, on the other hand, it was formed in the very thin film of 
liquid, which alone accompanied the plant on the roof of the air-chamber, it 
escaped into the air as fast as it was produced, and left the fungus unchanged. 
And this view is strongly confirmed by another fact, which I observed at the 
