Chapter IV (3)

Since writing this paragraph, we have found in M. Ch. Robin’s _Journal
d’Anatomie et de Physiologie_, an article signed by that gentleman,
and entitled _Sur la Nature des Fermentations_, &c. (July-August,
1875), in which the learned microscopist says:—“The _torula cerevisiæ_
is derived from the _mycoderma cerevisiæ_. My observations leave no
doubt on my mind that _penicillium glaucum_ is one of the forms
evolved from spores or ferments that have preceded it, as M. Trécul
showed a long time ago, and that, moreover, the spores of
_penicillium_, germinating in suitable media, give us the sporical
form termed _mycoderma_.”

We take the liberty to observe that these assertions of M. Robin’s are
purely gratuitous. Up to the present time it has been impossible to
discover a suitable medium for the proof of these different
transformations or polymorphisms. From the time of Turpin, who firmly
believed that he had observed these changes, to our own, none of the
microscopists who have affirmed these transformations have succeeded
in adducing any convincing proof of them, and M. Trécul’s latest
observations, especially as regards _penicillium_ and its
transformation into ferment or into the _mycoderma_ of beer, have been
positively disproved by ours, supported, as they are, by proofs that
we consider irrefutable.

Footnote 66:

It is a very easy matter to study the liquids and growths in our
flasks during the course of a single experiment. We take out the glass
stopper that closes the india-rubber tube on the straight-neck, and,
by means of a long rod or a glass tube previously passed through the
flame, take up a quantity, which we draw out immediately for
microscopical examination. We then replace the glass stopper, taking
care to pass it through the flame before doing so, to burn up any
organic particles of dust that it may have picked up from the table on
which we laid it.

Footnote 67:

We may prove the occurrence of alcoholic fermentation by the cells of
submerged _mycoderma vini_ in a different manner. To do this, after
having made all our preparations as before and shaken up the film of
_mycoderma vini_ in its liquid, we must attach our flask to a test
flask (Fig. 19), and pass the turbid liquid into the latter. On
succeeding days we shall detect a very protracted fermentation in the
test flask; there will be a succession of minute bubbles rising from
the bottom, but in small number at a time. The fermentation is very
evident whilst it lasts, but is rather sluggish, and, although of very
long duration, ceases long before the sugar is exhausted.

This experiment proves better than any other the non-transformation of
_mycoderma vini_ into other ordinary fungoid growths. For after
decanting the liquid into the test flasks, the sides of the
experimental flask remain covered with streaks of _mycoderma vini_
along with some of the liquid. Moreover, the flask is refilled with
air, and this air is being constantly renewed, in part, by variations
of the temperature of the oven, so that the _mycoderma_ remaining on
the sides is thus placed under the most favourable conditions for
transformation into other fungoid growths, if that were possible. It
is still more easy to detach the experimental from the test flask, and
to pass pure air into it, once or twice a day, or constantly. In any
case, we shall never see anything besides the _mycoderma vini_ spring
up within it.

Footnote 68:

See PASTEUR, _Comptes rendus des Séances de l’Académie des Sciences_,
t. liv., 1862, and t. lv., 1862. _Études sur les Mycodermes, &c._

Footnote 69:

In a subsequent chapter we shall prove that yeast is likewise
incapable of transformation into _mycoderma vini_.

Footnote 70:

We secured the purity of our mycoderma by the same means that we have
already described for the procuring of spores of _penicillium_ or
other fungoid growths in a state of purity.

Footnote 71:

BUFFON, _Histoire de l’Homme_, t. viii., edition 12mo, 1778; TURPIN,
_Mémoires de l’Académie des Sciences_, t. xvii.; Dr. PINEAU, _Annales
des Sciences Naturelles_, t. iii., 1845; POUCHET, _Traité de la
Génération dite Spontanée_, p. 335, 1859. See also our _Mémoire sur
les Générations dites Spontanées_, 1862, pp. 100 and following, in
which we give a _resumé_ of some of these theories.

Footnote 72:

The following is Turpin’s application of his theory to the formation
of the ferments of fruits (_Mémoires de l’Académie_, t. xvii., 1840,
p. 155), where also, on p. 171 the above quotation will be
found:—_Ferments Produced by the Filtered Juice of the Pulp of
Different Fruits_—“By the word pulp we mean the soft and juicy
cellular tissue of the fleshy part, mesocarp or middle layer of the
pericarp of certain ripe fruits. This cellular tissue, which is very
abundant in the peach and all stone-fruit, in the apple and pear, in
the orange and grape, and similar fruits, is the same as that which
forms the body of a leaf. Being in every case composed of a simple
agglomeration of contiguous mother-vesicles, which are always filled
with globulines that are more or less developed, more or less
coloured, and individually endowed with a special vital centre, it is
not surprising that its globulines when free and detached from the
compound organisms to which they belong, and from association with its
vegetable life, should, when placed in a suitable medium, themselves
vegetate and become transformed, under these new influences, into a
mucedine, with filaments and articulations. Such are the very fine,
and, consequently, very transparent globulines, which, when left to
themselves in sweetened water, grow and become vesicular, producing
other globulines in their interior, then bud, vegetate into mucedinous
filaments, decompose sugar, and produce all the effects that
constitute what we term _alcoholic fermentation_.”

Footnote 73:

BÉCHAMP, _Recherches sur la Nature et l’Origine des Ferments (Annales
de Chimie et de Physique, 4^e série_, t. xxiii., and _Comptes rendus
de l’Académie des Sciences_, Oct. 23, 1871).

Footnote 74:

We need scarcely here observe, having done so on previous occasions,
that whenever we opened our flasks to obtain specimens, we made use of
a fine tube, previously passed through the flame of a spirit lamp, and
that we also passed this flame over the surface of the india-rubber,
glass stopper, &c., to consume the organic particles of dust which
floating about might introduce themselves at the moment when we opened
the right-hand tube of the flask.

Footnote 75:

Ever since the year 1861 (see p. 92), this question of the possible
transformation of the ordinary fungi, especially _penicillium_ and
_mucor mucedo_, into yeast has engaged our attention. The results
attained have been entirely negative; but hitherto only the
conclusions of our work have been published, some account of which was
given at the meeting of the _Société Philomathique_ of March 30th,
1861. The following extract is from the _Bulletin_ of the
society:—“Meeting of March 30th, 1861. At this meeting a paper was
read by M. Pasteur ‘On the supposed changes in the form and vegetation
of yeast-cells, depending on the external condition of their
development.’ It is well-known that Leuwenhoeck was the first to
describe the globules of yeast, and that M. Cagnard-Latour discovered
their faculty of multiplying by budding. This interesting vegetable
organism has been the subject of a host of researches by chemists and
botanists. The latter, from the days of Turpin and Kutzing, have
almost unanimously regarded yeast as a form of development of various
inferior vegetable types, especially _penicillium_. The studies of
this subject which seem to have won most favour during the last few
years are those of MM. Wagner, Bail, Berkeley, and H. Hoffmann. The
researches of these botanists seem to strengthen and confirm the
original observations of Turpin and Kutzing. M. Pouchet has, quite
recently, expressed the same ideas, and has determined certain points
in connection with them with much precision of detail. M. Pasteur has
long studied this important question, which is so intimately connected
with the essential nature of yeast and with those phenomena of the
polymorphism of the inferior types of vegetable life, to which most of
the remarkable works of M. Tulasne relate; he has, however, arrived at
results that are altogether negative, and he declares that he was
unable to detect the transformation of yeast into any of the
_mucedines_ whatsoever, and, inversely, that he could never succeed in
producing the smallest quantity of yeast from ordinary _mucedines_.”
These same results we communicated to the _Société Chimique_ of Paris,
at a meeting held April 12th, 1861. Throughout the investigation of
which we have just indicated the conclusions, we insisted on the
necessity of cultivating the separate organisms in a state of purity
in all researches relating to these inferior forms of life, if we
desire to attain to sure inferences about them; and the method of
working, which we recommended, did not differ essentially from that
adopted in the present work. Since then the study of these growths has
been conducted with the utmost precautions; and other apparatus,
perhaps as safe as those which we employ and better adapted than ours
for the study of polymorphism of species, have been invented by
botanists of great skill—M. de Bary, in Germany, and M. Van Tieghem,
in France.

Footnote 76:

We found, after the lapse of another year, in December, 1873, that the
ferment of the _mucor_ in the test glass might still be easily
revived; that it was able to propagate, both in the mycelium and in
the cellular form, in wort, and that it might produce a fermentation,
more or less active, according to the condition of aeration; in short,
that it was capable of producing all the characteristic phenomena
described. By means of the method of cultivation that we employ, our
study, which was continued for years, was pursued without the least
fear of any foreign fungoid growths being introduced into the vessels,
although they remained constantly open, and the air in them was being
perpetually renewed by the action of diffusion and variations of
temperature. In 1875 nothing remained alive in our flask, and further
revival became impossible.

Footnote 77:

We do not here take into account certain phenomena of oxidation of
which the fungoid growths are the seat, and which remind us of those
that are presented in so remarkable a degree by _mycoderma vini_ and
_mycoderma aceti_.

Footnote 78:

[There are 15·43 grains in the gramme.]

Footnote 79:

[For English equivalent see Experiment 1, p. 135.]

Footnote 80:

The figure given below supplies this omission. The cells that are
isolated or are in chains, _b.b.b._, show this state of the old cells.
The cells _a.a.a._ are younger, and may be more easily revived. We may
see by the dimensions of some of these how greatly, in certain cases,
the cells of _mucor_ resemble cells of yeast; nevertheless, in the
state of the contents and the aspect of the outlines, there are always
some differences sufficiently appreciable to strike the practised
observer.

The figures adjoining the cells indicate fractions of a millimetre. (A
millimetre may be taken as ½5-in.)

Footnote 81:

[0·000089 in., 0·00026 in. and O·00089 in. respectively.]