36 THE EARLIER RESEARCHES ON DIASTATIG FERMENTS. [BOOK II. 



(Buccal Mucus). 



Water in 1000 parts . . . 99O02 

 Solids . L . . . . 9-98 



Organic matters soluble in alcohol 1'67 



insoluble 2*18 



Salts containing chiefly sodium") , 

 chloride and phosphate j 



According to Jacubowitsch 1 this fluid has no diastatic action. 



The glands of the mucous membrane covering the tongue of the 

 frog secrete a viscid liquid endowed, according to Le'pine, with 

 diastatic enzyme. 



SECT. 3. THE DIASTATIC ENZYME OF SALIVA AND THE ACTION 

 WHICH IT EXERTS UPON STARCH. 



Historical Sketch. 



Discovery of It was Leuchs 2 who ascertained that when saliva is 

 the amyioly- mixed with starch it gradually dissolves it with the 

 tic action of formation of a body which possesses the reactions of 

 saliva. grape-sugar. Schwann 3 confirmed this discovery, the 



truth of which soon received general assent, though the great majority 

 of scientific men declared themselves of the opinion that in the 

 living organism the saliva could not exert this action to an appre- 

 ciable extent, and that its function depended essentially upon its 

 watery character aiding gustation, mastication and deglutition 4 . 



Researches In 1845 Mialhe 5 discovered that when filtered 



ofMiaihe. human saliva is mixed with five or six times its 



weight of absolute alcohol, a small quantity of a flocculent body is 

 deposited, which he collected and dried at the temperature of the 

 air. This body he found to be insoluble in strong alcohol, but 

 partly soluble in water and very weak alcohol. He discovered its re- 

 markable property of converting boiled starch into sugar, and from 

 the resemblance to, indeed the apparent identity with, the amylolytic 

 ferment which Payen and Persoz had lately separated from germi- 

 nating barley 6 , he applied to it the name of animal or salivary 



1 Virchow in Ann. d. Charite. Berlin, 1858. 



2 Leuchs, Kastner's Archiv, 1831, quoted by Frerichs in his article 'Verdauung' 

 in Wagner's Handworterbuch d. PhysioL, Vol. in. Part i. p. 768. 



3 Schwann, Poggendorff s Annalen, Vol. xxxvui. p. 358. 



4 Consult Frerichs's brief sketch of the history of this subject (see note 2). 



5 Mialhe, <De la Digestion et de 1'Assimilation des Matieres sucre"es et amiloi'des.' 

 Comptes Eendus des seances de V Academic des Sciences. Vol. xx. Part i. p. 954. It 

 must be remembered that long before the researches of Payen and Persoz, Kirchhof had 

 observed that in the process of malting, a sugar is produced. Consult Brown and 

 Heron, 'Contributions to the History of Starch and its Transformations.' Journ. Chem. 

 Soc. t Vol. xxxv. p. 596 et seq. 



6 Payen et Persoz, 'Me*moire sur la Diastase, et les principaux Produits de ses 

 Reactions.' Comptes Rendus, and Annales de Cliimie et de Physique, Vol. LIII. (1833), 

 p. 73. 



