458 



DIGESTION. 



addition of salts the dialyzed saliva becomes active again, especially 

 on the addition of calcium or potassium chloride (see also page 71). 

 ROGER 1 believes that the presence of phosphates is a necessity for the 

 action of saliva. The amount of salts added is of special importance 

 for the action of the saliva, and one salt, which in small quantities has 

 an accelerating action, may in large quantities have a retarding action. 

 The presence of peptone has an accelerating action on the sugar forma- 

 tion (CHITTENDEN and SMITH and others). 



To show the action of saliva or ptyalin on starch the three ordinary 

 tests for glucose may be used, namely, MOORE'S or TROMMER'S test or 

 the bismuth test (see Chapter III). It is also necessary, as a control, 

 to first test the starch-paste and the saliva for the presence of glucose. 

 The steps in the transformation of starch into amidulin, erythrodextrin, 

 and achroodextrin may be shown by testing with iodine. 



Maltase occurs in saliva to only a slight extent. It converts maltose 

 into glucose. According to STICKER, 2 saliva also has the power of split- 

 ting sulphureted hydrogen from the sulphur oils of radishes, onions, 

 and certain other vegetables. 



The quantitative composition of the mixed saliva must vary consider- 

 ably, not only because of individual differences, but also because under 

 varying conditions there may be an unequal division of the secretion 

 from the different glands. We give herewith a few analyses of human 

 saliva as examples of its composition. The results are in parts per 1000. 



^uyenot, Compt. rend, soc, biol., 63; Roger, ibid., 65; see also Bang, Bioch. 

 Zeitschr., 32 (1911). 



2 Munch, med. Wochenschr., 43. 



Zeitschr. f. physiol. Chem., 5. The other analyses are cited from Maly, Chemie 

 der Verdauungssafte, Hermann's Handbuch d. Physiol., 5, Part II, 14. 



