262 AMYLOLYTIC POWER AND CHEMICAL 



From these results it would appear that saliva secreted after 

 a period of glandular inactivity, as before breakfast, is ordi- 

 narily possessed of greater amylolytic power than the secretion 

 obtained after eating; results which accord closely with 

 Hofbauer's observations. Before and after dinner (1 p. M.), 

 however, the difference hi amylolytic power is less pro- 

 nounced ; a fact which might be expected in view of the short 

 period for recuperation between the breakfast and dinner and 

 because of the more or less constant stimulation of the salivary 

 glands during the waking hours. Further, we see in these 

 results a suggestion of some degree of relationship between 

 the percentage of alkaline salts contained in the saliva and its 

 amylolytic power. Before breakfast, for example, the content 

 of alkaline salts and the starch-digesting power of the secre- 

 tion are greater than in the fluid secreted after glandular 

 activity. At first glance, then, it might seem that the varia- 

 tions in amylolytic action noticed above are due to changes in 

 the proportion of alkaline salts. The objection to this view, 

 however, is that it associates the higher degree of amylolytic 

 power with the higher percentage of alkalinity, whereas 

 numerous trustworthy experiments tend to show that saliva 

 manifests its highest degree of digestive power in a perfectly 

 neutral fluid.* Consequently, if the above variations in 

 amylolytic action are primarily due to changes in the propor- 

 tion of alkaline-reacting salts, then the higher degree of 

 amylolysis should be connected with the lower degree of 

 alkalinity. As the reverse is true, the more plausible and 

 natural explanation of the results is that the higher degree of 

 amylolysis is connected primarily with the presence of larger 

 amounts of the amylolytic enzyme, and as this is presumably 

 connected with the outpouring of a more concentrated secre- 

 tion a corresponding increase in alkaline-reacting salts might 

 naturally be expected. Further, in harmony with the latter 

 view it is to be noticed that the secretions obtained before and 



* Langley and Eves, Journal of Physiology, 1883, iv, p. 18. Chitten- 

 den and Smith, Studies in Physiological Chemistry, Yale University, 1885, i, 

 p. 8. 



