42 ACTION OF SALIVA UPON STARCH. [BOOK II. 



3 -4 12 grammes of starch boiled in 100 c.c. of water were digested at 

 40 C. with 100 c.c. of dilute human saliva for 15 hours, and their products 

 subjected to the previously described process : 



3-412 grammes starch yielded 0-505 grammes dextrin 



2-838 maltose 



3-343 



Whilst the nature and characters of the sugar which is produced 

 are not the subject of dispute, considerable divergence of opinion ex- 

 ists as to the number and the character of the individual dextrins 

 which are the ultimate products of the action of a diastatic ferment 

 on starch. The most recent researches on the subject, by Brown and 

 Morris, have led these observers to the conclusion that the physical 

 and chemical properties of the different dextrins precipitable at 

 several successive stages of the process may be accounted for on the 

 supposition of their being mixtures of maltose with one definite 

 achroodextrin which is entirely free from reducing power and which 

 has a specific rotation (a)D = 194*8 and (a)j = 216. The above 

 dextrin was obtained in a state of freedom from maltose by sub- 

 jecting it to the action of Knapp's reagent, viz. heating it with a 

 solution of cyanide of silver in solution of sodium hydrate. 



Maitodextrin. J n addition to this achroodextrin and maltose, and 

 having properties which more nearly resemble the latter than the 

 former, there occurs, at least under certain circumstances, a body 

 first obtained in an impure condition (i.e. contaminated with mal- 

 tose) by Herzfeld, which is possessed of reducing powers, whose 

 specific rotation is for (a) j = 1931 and for (a)D = 174'5 ; to this 

 body Brown and Morris retain the name of maltodextrin ascribed to 

 it by Herfeld. 



_ __ .. This question cannot be answered with complete 



IS Maltose ^ -r> i TT i . i 



the only Sugar precision. Brown and Heron nave shewn that the 

 produced by diastatic ferment of pancreatic juice possesses the 

 the action of property, which is not possessed by malt-diastase, of 

 saliva on transforming a small proportion of maltose into dex- 



trose, when the action is prolonged. Reasoning on the 

 ground of the apparent identity of the actions of the Salivary and 

 Pancreatic diastatic ferments in their mode of action on starch, we 

 should be inclined to surmise that the ultimate products resulting 

 from the two ferments would be the same. It must be stated, how- 

 ever, that in his research Lea did not obtain evidence of the forma- 

 tion of any sugar but maltose. 



1 Brown and Heron, ' Some Observations upon the Hydrolytic Ferments of the 

 Pancreas and small Intestine.' Proceedings of the Royal Society, 1880, p. 393. 



