AEROBIC AND ANAEROBIC RESPIRATION. 67 



splitting of the sugar molecule. Such an assumption finds physiological 

 substantiation in the fact established by Bertrand, 1 that oxidases are not 

 capable of directly oxidizing carbohydrates. The extensive researches of 

 Godlewski and of the Russian school of Palladin and Kostytschew have 

 made notable experimental contributions to a clearer understanding of this 

 subject. 



It is still a matter of dispute as to what are the agencies which effect this 

 disruption of the sugar molecule. By some it has been maintained that all 

 respiration has as its beginning zymase fermentation, and that the products 

 of this action are then oxidized to form the familiar products of aerobic 

 respiration. However, the results of Kostytschew" and others make it 

 appear highly improbable that the higher plants oxidize alcohol formed 

 either as an intermediate product or when given the plant as nutrient. 

 Kostytschew and Palladin 5 also showed that some plants exhibit a mixed 

 type of anaerobiosis in which the nature of sugar disintegration is different 

 from the regular zymase fermentation. In potatoes the amount of alcohol 

 formed was exceedingly small ; while from the results with various leaves 

 they conclude that about one-half of the CO 2 production is the result of 

 zymase action, the rest of the CO 2 resulting from a different form of gly- 

 colysis. It is to be concluded, then, that in the plant sugar disintegration 

 may follow several courses concomitantly, and that the nature of the main 

 metabolic product depends upon which of these courses is favored. This is, 

 of course, just what would be expected from a consideration of the behavior 

 of sugar solutions under the influence of various catalytic agents as revealed 

 by the extensive investigations of Nef, which have been already discussed. 



It seemed, therefore, not without interest to determine how the cacti, 

 which under normal conditions exhibit a rather modified course of respira- 

 tion, behaved under anaerobic conditions. The procedure consisted essen- 

 tially of expressing the juice from 200 grams of the ground cactus and 

 determining the alcohol in this juice. 4 A small portion of the juice was 

 used for the determination of acidity ; the remainder was used for the alcohol 

 determinations. By addition of calcium carbonate, the juice was made 

 neutral. To this neutralized juice there was added ammonium sulphate, 

 75 grams of the salt to each 100 c. c. of juice. This was carried out in a 

 wide-mouth bottle and, after the addition of the ammonium sulphate and a 



I BEKTRAND, G. Sur les rapports qui existent enter la constitution chemique des 



composes organiques et leur oxidabilite sous 1'influence de la laccase. Comp. 



rend., 122, 1132, 1896. 

 MATHEWS, A. P. The spontaneous oxidation of sugars. Jour. Biol. Chem., 6, 1-20, 



1909. 

 'KOSTYTSCHEW, S. Ueber den Zusammenhang der Sauerstoffatmung der Samen- 



pflanzen mit der Alkoholgaerung. Ber. d. deut. bot. Ges., 26, 565-573, 1908. 



3 PALT.APIN, W., and S. KOSTYTSCHEW. Ueber die anaerobe Atmung der Samen- 



pflanzen ohne alkohol bildung. Ber. d. deut. bot. Ges., 25, 51-56, 1907. 

 KOSTYTSCHEW, S. Ueber das Wesen der anaeroben Atmung verschiedener Samen- 

 pflanzen. Ber. d. deut. bot. Ges., 31, 125-129, 1913. 



4 Dox, AETHUB W., and A. R. LAMB. An accurate aeration method for the determina- 



tion of alcohol in fermentation mixtures. Jour. Amer. Chem. Soc 38 2561- 

 2568, 1916. 



