Let us now return to the first experiment described in the
paragraph on page 292 in which a flask of three litres capacity
was filled with fermentable liquid, which, when caused to
ferment, yielded 2.25 grammes of yeast, under circumstances where
it could not obtain a greater supply of free oxygen than 16.5 cc.
(about one cubic inch). According to what we have just stated, if
this 2.25 grammes (34 grains) of yeast had not been able to live
without oxygen, in other words, if the original cells had been
unable to multiply otherwise than by absorbing free oxygen, the
amount of that gas required could not have been less than 2.25 X
4l4 cc., that is, 931.5 cc. (56.85 cubic inches). The greater
part of the 2.25 grammes, therefore, had evidently been produced
as the growth of an anaerobian plant.
Ordinary fungi likewise require large quantities of oxygen for
their development, as we may readily prove by cultivating any
mould in a closed vessel full of air, and then taking the weight
of plant formed and measuring the volume of oxygen absorbed. To
do this, we take a flask of the shape shown in Fig. 8, capable of
holding about 300 cc. (10 1/2 fluid ounces), and containing a
liquid adapted to the life of moulds. We boil this liquid, and
seal the drawn-out point after the steam has expelled the air
wholly or in part; we then open the flask in a garden or in a
room. Should a fungus-spore enter the flask, as will invariably
be the case in a certain number of flasks out of several used in
the experiment, except under special circumstances, it will
develop there and gradually absorb all the oxygen contained in
the air of the flask. Measuring the volume of this air, and
weighing, after drying, the amount of plant formed, we find that
for a certain quantity of oxygen absorbed we have a certain
weight of mycelium, or of mycelium together with its organs of
fructification. In an experiment of this kind, in which the plant
was weighed a year after its development, we found for 0.008
gramme (0.123 gram) of MYCELIUM, dried at 100 degrees C. (212
degrees F.), an absorption that amounted to not less than 43 cc.
(2.5 cubic inches) of oxygen at 25 degrees. These numbers,
however, must vary sensibly with the nature of the mould
employed, and also with the greater or less activity of its
development, because the phenomena is complicated by the presence
of accessory oxidations, such as we find in the case of mycoderma
vini and aceti, to which cause the large absorption of oxygen in
our last experiment may doubtless be attributed. [Footnote: In
these experiments, in which the moulds remain for a long time in
contact with a saccharine wort out of contact with oxygen--the
oxygen being promptly absorbed by the vital action of the plant
(see our Memoire sur les Generations dites Spontanees, p. 54.
note)--there is no doubt that an appreciable quantity of alcohol
is formed because the plant does not immediately lose vital
activity after the absorption of oxygen.
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