434 



DIGESTION. 



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

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

 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 dextrose. According to STICKER 1 saliva also has the power of split- 

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

 and certain other vegetables. 



The quantitative composition of the mixed saliva must vary considerably, 

 not only because of individual differences, but also because under vary- 

 ing 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. 



HAMMERBACHER found in 1000 parts of the ash from human saliva: potash 

 457.2, soda 95.9, iron oxide 50.11, magnesia 1.55, sulphuric anhydride (S0 3 ) 63.8, 

 phosphoric anhydride (PA) 188.48, and chlorine 183.52. 



The quantity of saliva secreted during twenty-fours hours cannot 

 be exactly determined, but has been calculated by BIDDER and SCHMIDT 

 to be 1400-1500 grams. The most abundant secretion occurs during 

 meal-times. According to the calculations and determinations of TuczEK, 3 

 in man 1 gram of gland yields 13 grams of secretion in the course of one 

 hour during mastication. These figures correspond fairly well with those 

 representing the average secretion from 1 gram of gland in animals, 



1 Munch, med. Wochenschr., 43. 



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

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



3 Bidder and Schmidt, 1. c., 13; Tuczek, Zeitschr. f. Biologic, 12. 



