1888.] On the Secretion of Saliva. 17 



of chorda saliva, and yet contain very nearly as high a percentage of 

 salts. 



Dyspnoea decreases the rate of secretion of saliva with a given 

 stimulus, and if not too prolonged, increases the percentage of salts, 

 and tends to increase the percentage of organic substance in the saliva. 

 This holds whether the saliva be obtained by stimulating the chorda 

 tympani, or by injecting pilocarpin. Dyspnoea has, for a short time, 

 an after-action, tending also to increase the percentage of salts, and 

 possibly that of organic substance. 



Clamping the carotid during secretion has the same general effect 

 as dyspnoea, but it causes a still more marked increase in the per- 

 centage of salts. Its after-effect is also much greater, and lasts longer. 



Bleeding has a similar effect to dyspnoea and to clamping the 

 carotid, but its most marked effect is an increase in the percentage of 

 organic substance. 



Injection of dilute salt solution, NaCl, 0'2 to 0'6 per cent., in sufficient 

 quantity, considerably increases the rate of secretion of saliva ; the 

 percentage of salts in the saliva decreases, although the rate of 

 secretion of salts usually increases ; the percentage of organic sub- 

 stance decreases ; that is, increasing the volume of the blood with 

 dilute salt solution chiefly increases the rate of secretion of water. 



The percentage of salts in samples of saliva obtained after the 

 injection of dilute salt solution, increases with the rate of secretion, it 

 is only when these are obtained before the injection that a discrepancy 

 in the normal relation between percentage of salts and rate of secre- 

 tion of water appears. 



Injection of sodium carbonate 2 per cent, also increases the rate of 

 secretion of saliva ; in this case the percentage of salts is about normal, 

 the percentage of organic substance falls slightly only, i.e., the irrita- 

 bility either of the nerve-fibres or of the gland cells is increased. 



Injection of considerable doses of potassium iodide, 1 per cent., after 

 the sodium carbonate still allows a rapid secretion, but the percentage 

 of salts falls. 



Injection of strong salt solution increases the percentage of salts in 

 saliva, this is in accordance with the recent observations of Novi 

 that the chlorine in the salts of saliva is increased for a given rate of 

 secretion by increasing the percentage of sodium chloride in the blood. 

 We find, however, that in the case of an injection of strong salt solution 

 into the blood which leaves the secretory power of the gland un- 

 affected, the increase in the percentage of salts is much greater with 

 slowly than with rapidly secreted saliva, and that when the secretory 

 power of the gland is affected by strong salt solution, an increase in 

 the percentage of organic substance also takes place ; this and a part 

 of the increase in the percentage of salts we attribute to a decrease of 

 the blood- flow through the gland. 



VOL. XLV. 



