INTRODUCTORY DISCUSSION. 19 



the breaking of the 1, 2 hexose dienol and subsequent immediate oxidation 

 would result in the formation of formic and d-arabonic acids. All these 

 actions proceed simultaneously, the final products depending upon the 

 conditions favoring the one or the other. By vigorous oxidation, as for 

 instance the use of copper hydroxide or silver oxide, the products of the more 

 complete dissociation are oxidized to form the corresponding acids, while 

 with air or hydrogen peroxide the final products formed are from the 

 immediate oxidation of the dissociated sugar molecule. 



On account of their great reactivity it has not been possible as yet to 

 determine definitely the composition of all the fragments resulting from 

 the dissociation of the sugars. The principle, however, of salt formation 

 and subsequent dissociation seems well established. Of greatest importance 

 to the problem of metabolism is the fact that precursory to the oxidation of 

 sugars is the dissociation or rearrangement of the molecule into a large 

 number of pieces of high reactivity and that these products of dissociation 

 are capable of the most multifarious reactions depending upon various con- 

 ditions, such as concentration, temperature, and the presence of oxygen. 



Prom a survey of the phenomena of oxidation over the very extensive 

 range of chemical substances, it becomes evident that a primary dissocation 

 is conditio sine qua non before oxidation can take place. This conception in 

 one form or another is of greatest importance to the physiologist in the 

 interpretation of phenomena of catabolism, but has been considered very 

 little by plant physiologists. That pure aqueous solutions of sugars are 

 relatively stable has led to many misconceptions and the formulation of 

 elaborate hypotheses as to the process and agents inducing glycolysis. It 

 need hardly be mentioned that conditions in the cell are very different, that 

 the reactions do not take place in pure water solution, but largely in a 

 colloidal mixture in the presence of a large variety of inorganic salts, and 

 that such conditions lead to a dissociation of the sugar molecule. The role 

 and mode of function of enzymes is in all probability a special form of this 

 group of reactions. In fact, it seems doubtful that for these reactions, at 

 least, it is necessary to assume that the sugars are first organized into a large 

 " biogen " molecule in the cell prior to the release of energy or oxidation. 

 Such an assumption lies quite outside of the range of scientific investigation. 



By means of the treatment with calcium salts of organic acids, the 

 products of dissociation of the dextrose molecule are capable not only of 

 rearrangement and oxidation, but also of union to form polysaccharides and 

 more complex substances. 1 



The relatively simple dissociation of sugars by means of alkali must 

 yield considerable energy, as Nef observed a decided rise in temperature 

 on mixing the solutions." It would be exceedingly interesting to have 

 accurate experimental data on this point. 



The questions relative to the mechanism of the utilization of energy in 

 the vegetable organism have as yet not been stated by plant physiologists 



* NEF, J. U. Liebig's Annalen, 403, 226-234, 373, 1913. Ibid., 376, 12, 1910. 



