COMPOSITION OF HUMAN MIXED SALIVA. 269 



digesting power. Simple mastication of rubber has a marked 

 influence in raising the content of alkaline salts in the saliva, 

 as well as the total inorganic constituents, and there is a ten- 

 dency toward increase in amylolytic power, although the latter 

 is not constant. 



As to the influence of alcohol, ether, gin, and whiskey, there 

 is, we think, no question that these agents taken into the 

 mouth change the character of the secretion, increasing its 

 alkalinity, amylolytic power, and content of solid matter. This 

 is certainly true if the secretion so obtained is compared with 

 the saliva flowing from the mouth without stimulation of any 

 kind. Saliva, however, secreted under the stimulation produced 

 by chewing rubber is, as we have seen, comparatively con- 

 centrated, and the difference between the secretion resulting 

 from that method and the fluid coming from ether, alcohol, 

 and other like forms of excitation, without mechanical stimula- 

 tion, is not so decisive in the above experiments as to make the 

 matter quite clear, especially in view of the fact that two 

 portions of saliva obtained one after the other, by the same 

 method of stimulation, are liable to show marked differences in 

 composition and reaction. Particularly noteworthy is the fact 

 that of two portions of saliva collected one after the other by 

 mechanical stimulation (chewing rubber) or by simply allowing 

 the sali va to flow from the mouth after once rinsing the latter 

 with water, the latter portion of saliva is, as a rule, more con- 

 centrated and possessed of higher amylolytic power than the 

 portion first secreted. It is thus obvious that great care must 

 be exercised in drawing deductions from the composition and 

 amylolytic action of mixed sali va when the latter is so prone 

 to vary under what seem to be essentially the same forms of 

 stimulation. It is furthermore equally obvious that the 

 possible causes to which the above variations may be attributed 

 are many, since there are involved three distinct sets of glands 

 in addition to the buccal glands of the mouth cavity. Hence, 

 increase or decrease in amylolytic power, as well as in the 

 general concentration of the secretion, may involve simply an 

 alteration in the relative activity of the individual glands and 



