288 SCIENCE PROGRESS 



he thought, a new sugar, revertose. Moreover, as already 

 mentioned, Frankland Armstrong thinks it doubtful whether 

 maltose is produced at all by the action of maltase, and that 

 revertose is really isomaltose. Emulsin, on the other hand, 

 which does not hydrolyse maltose, does produce this sugar, 

 though apparently in very small quantity. 



If we accept this point of view, we are landed in many diffi- 

 culties, as well as having to reject many experimental results of 

 other observers. Croft Hill, for example, found that the same 

 equilibrium point was reached whether he started from glucose 

 or from a mixture consisting chiefly of maltose — viz. for a 

 40 per cent, solution, equilibrium was arrived at when the per- 

 centage of maltose was 15 and that of glucose 85. This would 

 seem impossible if the synthetic product were isomaltose, on 

 which the enzyme present has no action. Since there is no 

 agent capable of hydrolysing the isomaltose formed, there is no 

 reason why the glucose should not be completely transformed 

 to this disaccharide. Again, as Croft Hill showed, the relative 

 percentages of glucose and " maltose " varied according to the 

 concentration of the original solution taken; in a 10 per cent, 

 solution, for example, the percentage of maltose is only 5 at 

 the equilibrium point. If, therefore, we were to take a 40 per 

 cent, solution of glucose and act upon it with maltase until the 

 15 per cent, of the synthetic disaccharide has been produced 

 and then dilute to four times its volume, if the synthetic sugar 

 formed were isomaltose it should remain unchanged, whereas, if 

 maltose, it would, of course, be hydrolysed back to glucose by the 

 enzyme present. This experiment has been performed by Croft 

 Hill with the result of hydrolysis back to glucose, according 

 to the latter of the two above alternatives. 



The results of Visser, who found that emulsin synthesised 

 salicin, the same glucoside which it hydrolyses, and that inver- 

 tase is able to synthesise cane-sugar, are also at variance with 

 Frankland Armstrong's results. 



It must be admitted, therefore, that further evidence is 

 necessary before we can accept this point of view of the syn- 

 thesis by enzymes of bodies which they do not hydrolyse. 



Croft Hill seems to suggest the possibility of more than one 

 enzyme being present in the preparations used. This suggestion 

 must be kept in mind, especially as the methods used by 

 Frankland Armstrong depend on the destruction of glucose or 



