In the _oxydative disintegration_ of dextrose, taking place in aërobic organisms, if sufficient quantities of oxygen are present, there occurs a splitting up of the carbohydrate molecule, as a result of the introduction of oxygen, into simpler substances and finally into carbon dioxide and water, just as the dextrose molecule, when subjected to oxydative processes, is split up into simpler molecules. In the living substance the oxydases play the important rôle of oxygen carriers. It cannot be denied, however, that up to now no carbohydrate splitting oxydases have been obtained from living substance. This, of course, does not prove its nonexistence. But this deserves consideration in connection with an assumption very widely spread among plant physiologists in regard to the aërobic disintegration of the carbohydrate molecule, which I shall touch upon presently. If we suppose that oxydases exist, which bring about primarily the oxydative disintegration of the dextrose molecule, its first point of attack must obviously be sought in the aldehyde group. Here would be situated the activator, as it were, for the whole carbon chain, from which, as by a spark, the entire series of links would be ignited. In an _anoxydative disintegration_ of dextrose as observed in anaërobic as well as in aërobic organisms, provided the latter have an insufficient supply of oxygen, the dextrose molecule, by enzymic action as a result of the splitting off of carbon dioxide, is converted into substances having a comparatively large carbon content. The best-known example of this anoxydative disintegration is the formation of alcohol by fermentation in which the dextrose molecule is split up by the yeast into alcohol and carbon dioxide. (C_{6}H_{12}O_{6} = 2C_{2}H_{5}OH + 2CO_{2}.) Instead of the production of alcohol and CO_{2} we may have other enzymic actions with the formation of other carbon-containing disintegration products, such as lactic acid, fatty acids, hydrogen, etc. Of course in such an anoxydative disintegration, which does not lead to the formation of such simple combinations as carbon dioxide and water, the _quantity_ of energy set free is much less in amount than in complete _oxydative_ decomposition, the energy production of the alcohol fermentation being only 11 per cent of the latter. In order to produce the same amount of energy as in the former, a much greater number of molecules is required. We find, therefore, that the anoxydative type of disintegration develops either only where the respiratory substances are present in sufficient amounts, as for instance, in the case of yeast cells, existing in nutritive solutions rich in sugar; or where the chemical and energy transformations occur only to a limited extent, as, for example, in the presence of low temperature. In this respect _Pütter_[59] has demonstrated in the leech that at a higher temperature, the oxydative, at a lower, the anoxydative, decomposition predominates. These are important facts