138 Physiologie. 



hydrolysed by hydrochloric acid the /^-glucosides are much 

 more rapidly affected than the corresponding a-compounds. 

 Aithoiigh the stereoisomerism is coniined to the terminal carbon 

 atom the galactosides are much more rapidly attacked than the 

 corresponding glucosides. It is surprising that the change 

 from glucose to galactose, affecting only the nature ol attach- 

 ment of the oxygen atoms in the ring, should have so marked 

 an influence on the activity of the group associated with the 

 terminal carbon atom. 



!t is probable that the active System in which the change 

 takes place is formed by association of acid-water-molecules 

 with the oxygen in the pentaphane ring. 



Ordinary yeast maltase hydrolyses maltase much more 

 readily than it does c-miethyl-glucoside and the action falls of 

 more rapidly in the case of maltase owing to the difference in 

 the products. Maltose produces two molecules of glucose 

 whereas «-methyl-glucoside only produces one and hence any 

 retardation depending on glucose ought to be less evident in 

 the latter case. 



The enzyme acts much more rapidly than the acid in 

 hydrolysis and since the molecular weight of the enzyme is 

 certainly high it would seem to iollow that the relative mole- 

 cular activity of the enzyme is much greater than that of the 

 acid; but since only a small proportion of the acid present is 

 usually active, the enzyme may owe its apparent activity to 

 greater aifinity for sugar, and in reality the acid may have the 

 greater hydrolytic activity. E. Drabble (London). 



Armstrong, E. F., St u dies on enzyme action. VI. The 

 Sucroclastic action of acids as contrasted with 

 that of Enzymes. Part II. (Proc. Roy. Soc. London. 

 Nov. 1, 1904.) 



The analogy between the action of acids and enzymes in 

 effecting hydrolysis of cane sugar is couiplete. In each case when 

 the Proportion of the hydrolyst is relatively small the change 

 is at first approximately a linear function of the time and sub- 

 sequentiy it becomes a logarithmic function. When a larger 

 proportion of the hydroiyst is present the change is from the 

 first a logarithmic function. The differences between acid- and 

 enzyme-hydrolysis can all be attributed to their respectively 

 crystalloid and colloid nature. It has been shown in a previous 

 memoir that the products of hydrolysis by acids increase the 

 rate of action apparently by combining with some of the water, 

 while in enzyme-hydrolysis they decrease it as previously ex- 

 plained. Working with sucrose the author finds that about the 

 same acceleration is produced by equimolecuiar proportions of 

 glucose or fructose while the biose cane sugar exercises about 

 twice the efiect of a monose. e. Drabble (London). 



