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.