WILL you permit me to point out art error which has crept into the report of my paper on “Brewing in Japan” in last week's NATURE, p. 468. After mentioning the points in which Koji differs from malt, the report continues:—“Koji is prepared as follows: a mixture of steamed rice and water is allowed to remain in shallow tubs at a low temperature (0°–5° C.) until quite liquid; it is then heated”, and so on. The following alterations will make the account of the Japanese brewing process correct:—“Sake (rice-beer) is prepared as follows: a mixture of steamed rice, koji, and water is allowed to remain in shallow tubs at a low temperature (0° – 5° C.) until quite liquid; it is then heated…”. Not using malt as we do in our breweries, the Japanese have discovered for themselves a means of rendering the rice-grains diastatic with allowing the embryo to germinate. This is effected by exposing the softened rice-grains to the action of dry steam, by which treatment the starch is gelatinised; when cold the spores of a mould are caused to grow over the surface of the rice, the mycelium being formed at the expense of the starch, and heat being liberated together with the usual products of combustion. The albuminoid matter of the rice, which previously was for the most part insoluble in water, is, after the growth of the mycelium, found to be almost completely soluble, and the solution possesses diastatic properties resembling those of malt extract. The main point in which it differs from the latter is in its superior hydrating power, for, unlike malt-extract, the solution of koji very quickly converts maltose into dextrose. This material (koji) is then used instead of malt in the mashing process, the sugar formed from the rice-starch under the influence of the dissolved koji being dextrose, which is further fermented by the accidental introduction from the atmosphere of the germs of a species of yeast. The change induced in the character of the albuminoid matter under the influence of the growing mould is remarkable, and, I think, novel, and the interest of the observations I have made lies in the support they give to the opinion that the diastatic property is connected with the degree of solubility of the albuminoid matter, and in the fact that this may result as well from the growth of an organism foreign to the grain as from the germination of the embryo itself.