AMYLOLYTIC ACTION OF SALIVA. 411 



undertaken by F. Kiibel * in Professor Griitzner's laboratory. 

 The results obtained are largely confirmatory of investigations 

 carried out long ago in this laboratory by Chittenden and 

 Smith.! As Kiibel was apparently not familiar with this 

 work, and inasmuch as other recent writers J have overlooked 

 some of the results long established, it seemed desirable to 

 review the older observations here very briefly and to add 

 some experiments of our own which may serve to explain and 

 extend the work of Kiibel. 



From careful quantitative experiments, in which the extent 

 of amylolytic action was determined by a direct estimation of 

 the sugar formed, Chittenden and Smith concluded as follows : 



" The most favorable condition for the diastatic action of 

 ptyalin, under most circumstances, appears to be a neutral 

 condition of the fluid together with the presence of more or 

 less proteid matter. The addition of very small amounts of 

 hydrochloric acid, however, to dilute solutions of saliva, 

 giving thereby a small percentage of acid-proteids, appears to 

 still further increase diastatic action. Under such conditions 

 a minute trace of free acid appears to still further increase the 

 action. 



" 0.003 per cent free hydrochloric acid almost completely 

 stops the amylolytic action of ptyalin. The larger the amount 

 of saturated proteids, the more pronounced becomes the 

 retarding action of free acids. 



" The retarding effects of smaller percentages of free acid 

 are not due wholly to destruction of the ferment. Pronounced 

 destruction takes place with 0.005-0.01 per cent free hydro- 

 chloric acid. 



" Proteid matter, in influencing the diastatic activity of 

 salivary ptyalin acts not only by combining with acids and 



Kubel, Archiv fur die gesammte Physiologic, 1899, Ixxvi, p. 276. 



t Chittenden and Smith, Studies from the Laboratory of physiological 

 Chemistry, Yale University, 1885, i, p. 1. Also transactions of the < 

 necticut Academy, 1885, vi, p. 343-. Jahresbericht fur Thierchemie, 1885, XT, 

 p. 256. 



J E.g., Austin, Boston Medical and Surgical Journal, 1899, cxl, p. 825. 



