which gives cacao its stimulating properties, but the
    estimation of theobromine in fermented and unfermented beans
    does not support this.

    (5) _Consistency._ Fermented beans become crisp on drying.
    This development may be due to the "tannins" encountering, in
    their dispersion through the bean, proteins, which are thus
    converted into bodies which are brittle solids on drying
    (compare tanning of hides). The "hide" of the bean may be
    similarly "tanned"--the shell certainly becomes leathery
    (unless washed)--but a far more probable explanation, in both
    cases, is that the gummy bodies in bean and shell set hard on
    drying.

    [3] _Journal of the Chemical Society_, 1912.

We see, then, that although fermentation was probably originally
followed as the best method of getting rid of the pulp, it has other
effects which are entirely good. It enables the planter to produce a
drier bean, and one which has, when roasted, a finer flavour, colour,
and aroma, than the unfermented. Fermentation is generally considered to
produce so many desirable results that M. Perrot's suggestion[4] of
removing the pulp by treatment with alkali, and thus avoiding
fermentation, has not been enthusiastically received.

    [4] _Comptes Rendus_, 1913.

Beans which have been dried direct and those which have been fermented
may be distinguished as follows:


CACAO BEANS

                       DRIED DIRECT.         FERMENTED AND DRIED.

_Shape of bean_     Flat                     Plumper
_Shell_             Soft and close fitting   Crisp and more or
                                                    less free.
_Interior: colour_  Slate-blue or mud-brown  Bright browns and
                                                    purples
   " _consistence_  Leather to cheese        Crisp
   " _appearance_   Solid                    Open-grained
   " _taste_        More or less bitter      Less astringent
                           or astringent

Whilst several effects of fermentation have not been satisfactorily
accounted for, I think all are agreed that to obtain one of the chief
effects of fermentation, namely the brown colour, oxidation is
necessary. All recognise that for this oxidation the presence of three
substances is essential:

     (1) The tannin to be oxidised.

     (2) Oxygen.

     (3) An enzyme which encourages the oxidation.

All these occur in the cacao bean as it comes from the pod, but why
oxidation occurs so much better in a fermented bean than in a bean which
is simply dried is not very clear. If you cut an apple it goes brown
owing to the action of oxygen absorbed from the air, but as long as the
apple is uncut and unbruised it remains white. If you take a cacao bean
from the pod and cut it, the exposed surface goes brown, but if you
ferment the bean the whole of it gradually goes brown without being cut.
My observations lead me to believe that the bean does not become
oxidised until it is killed, that is, until it is no longer capable of
germination. It can be killed by raising the temperature, by
fermentation or otherwise, or as Dr. Fickendey has shown, by cooling to
almost freezing temperatures. It may be that killing the bean makes its
skin and cell walls more permeable to oxygen, but my theory is that when
the bean is killed disintegration or weakening of the cell walls, etc.,
occurs, and, as a result, the enzyme and tannin, _hitherto separate_,
become mixed, and hence able actively to absorb oxygen. The action of
oxygen on the tannin also accounts for the loss of astringency on
fermentation, and it may be well to point out that fermentation
increases the internal surface of the bean exposed to air and oxygen.
The bean, during fermentation, actually sucks in liquid from the
surrounding pulp and becomes plumper and fuller. On drying, however, the
skin, which has been expanded to its utmost, wrinkles up as the interior
contracts and no longer fits tightly to the bean, and the cotyledons
having been thrust apart by the liquid, no longer hold together so
closely. This accounts for the open appearance of a fermented bean. As
on drying large interspaces are produced, these allow the air to
circulate more freely and expose a greater surface of the bean to the
action of oxygen. Since the liquids in all living matter presumably
contain some dissolved oxygen, the problem is to account for the fact
that the tannin in the unfermented bean remains unoxidised, whilst that
in the fermented bean is easily oxidised. The above affords a partial
explanation, and seems fairly satisfactory when taken with my previous
suggestion, namely, that during fermentation the bean is rendered
pervious to water, which, on distributing itself throughout the bean,
dissolves the isolated masses of tannin and diffuses it evenly, so that
it encounters and becomes mixed with the enzymes. From this it will be
evident that the major part of the oxidation of the tannin occurs during
drying, and hence the importance of this, both from the point of view of
the keeping properties of the cacao, and its colour, taste and aroma.

It will be realised from the above that there is still a vast amount of
work to be done before the chemist will be in a position to obtain the
more desirable aromas and flavours. Having found the necessary