COMPOSITION OF HUMAN MIXED SALIVA. 267 



curve independent of the fluctuations induced by stimuli. 

 Thus at 11.30 A. M. there is seen the same fall in amylolytic 

 power, that was so conspicuous in the preceding experiment. 

 Further, the saliva secreted at 2.15 P. M. shows a diminution 

 in amylolytic power, as noticeable as the diminution frequently 

 observed after a hearty meal. It is thus quite evident that in 

 the absence of food and other stimulation hourly changes in 

 the amylolytic power of mixed saliva may occur just as marked 

 as those noticed in the saliva secreted before and after break- 

 fast. Variations in alkalinity, total solids, etc., are not so 

 prominent. It is to be noticed, however, from the last series 

 of experiments, that in the absence of breakfast there is no 

 great variation in the amylolytic power of the saliva secreted 

 between 6.40 and 11.00 A. M. ; consequently we may accept 

 the conclusion, justified by the results of most of our experi- 

 ments, that the taking of food, as at breakfast, tends to lower 

 the starch-digesting power of the saliva secreted some time 

 thereafter. This being so, it seems probable that other forms 

 of stimulation may likewise give rise to a change in the com- 

 position and physiological action of mixed saliva. 



V. INFLUENCE OF VARIOUS STIMULI ON THE COMPOSI- 

 TION AND AMYLOLYTIC POWER OF HUMAN SALIVA. 



In this series of experiments the attempt was made to 

 ascertain how far the character of the stimulus modifies the 

 properties of mixed saliva. The special stimuli employed were 

 ether, alcohol, whiskey, and gin. The first two were taken 

 into the mouth in the form of vapor, and the saliva allowed to 

 trickle from the mouth without motion of the jaws, the fluid 

 so obtained being compared with saliva resulting from the 

 mechanical stimulation produced by chewing a piece of rubber. 

 With whiskey and gin, the mouth was well rinsed with the 

 fluid and the saliva collected by allowing it to flow from the 

 corner of the mouth. The control experiments with water 

 were made in the same way ; i. ., the mouth was rinsed with 

 water and the saliva allowed to trickle forth. Finally, for the 

 sake of comparison and to ascertain how far two samples of 



