50 CONVERSION OF STARCH INTO SUGAR. [BOOK II. 



complete hydration, the ternary compound being split off in the form of 

 malto-dextrin, when one of its sub-groups has been hydrated. thus : 



{P IT O 

 ^]2- n 22 V -'n 

 CO H O ) 

 V^12 J - 1 20 Vy iO/2 



One of the five Malto-dextrin. 



ternary groups con- 

 stituting the hypothetical 

 starch molecule. 



Under the influence of fresh diastatic ferment, acting under favourable 

 conditions, malto-dextrin readily undergoes the change indicated in the 

 following equation : 



(P TT O 

 ^i2 xl 22 w n +2ELO-3C H O 

 /p TT n \ ***v/ ov; .tig Wjj. 

 (t'MfWj 



Malto-dextrin. Maltose. 



These hypotheses, advanced to explain the action of malt extract on 

 starch, will apply mutatis mutandis to the changes induced by any diastatic 

 enzyme. 



Influence , 



of certain Carbohc acid, unless when present in the proportion 



poisonous of 5 per cent, of the starch jelly, does not interfere with 



agents on dia- the diastatic action of saliva, 

 static action. 



Salicylic acid possesses, on the contrary, a much more powerful 

 action. According to Julius Muller 1 , salicylic acid in the proportion 

 of 0'2 per cent., retards the action of saliva upon starch-paste, whilst 

 in the proportion of 1 per cent, it arrests it. Although, therefore, 

 susceptible in a high degree to the action of salicylic acid, the 

 diastatic salivary ferment is not so much so as diastase, as will be 

 again referred to in the sequel. 



Some poisons, as arsenious acid 2 , possess no power of influencing 

 the diastatic ferment of saliva; others, such as hydrocyanic acid, 

 possess this power only in a feeble degree and when present in large 

 quantities. 



is the dia- Although the ultimate products of the action of 

 static ferment the diastatic ferment of saliva and vegetable diastase 

 of the saliva appear to be identical, there are facts which conclusively 

 identical with proye the individuality of these two bodies. 



The following are certain points of difference between 

 malt-diastase and salivary ferment. 



1. Malt-diastase acts powerfully upon starch through a wide 

 range of temperatures ; its activity is greatest at 60 C., and then 



1 Miiller, 'Ueber die antiseptischen Eigenschaften der Salicylsaure, gegeniiber der 

 Carbolsaure.' Journ. f. prakt. Chemie, New ser., Vol. x. p. 45. 



2 Schafer and Bohm, ' Ueber den Einfluss des Arsens auf die Wirkung der unge- 

 formten Fermente.' VerhandL d. physik.-med. Gesellsch. in Wiirzburg, N. F. Vol. in. 

 p. 238. 



