228 APPLIED PHYSIOLOGY 



the influence of emotion, with the result that the saliva 

 then becomes sticky, and the tongue may ' cleave to the 

 roof of the mouth.' On the other hand, if the chorda 

 tympani be paralyzed, as it is in some cases of facial nerve 

 palsy, the saliva is more scanty. Division of the secretory 

 nerves leads after a time to the appearance of a steady 

 flow of saliva, spoken of by physiologists as a * paralytic 

 secretion,' which may last for some days. It has been 

 suggested that the ptyalism met with in cases of bulbar 

 paralysis is of this nature, but against such an explana- 

 tion is its long persistence. 



The secretory nerves of the salivary glands are sus- 

 ceptible to the influence of certain drugs. Atropine, for 

 instance, paralyzes the terminals of the cranial fibres, 

 and diminishes the flow ; whilst pilocarpine, by stimu- 

 lating them, exerts an opposite effect. Hence dryness 

 of the mouth is one of the unpleasant consequences 

 of the exhibition of atropine, whilst pilocarpine is used 

 as a remedy in cases of diminished salivary secretion 

 (xerostomia). 



The salivary glands also possess a degree of excretory 

 power for some substances. We know that certain 

 drugs, for instance, are so excreted. Chlorate of potash 

 is a case in point : when swallowed in solution it is 

 partly excreted by the saliva, and may thus exert a 

 local effect upon the mouth. It is useful in this way in 

 cases of stomatitis. Again, ' a bad taste in the mouth ' 

 is probably due, in some cases at least, to the excretion 

 of abnormal substances by the salivary glands. 



