ON THE SECRETION OF SALIVA. 
153 
nerve stimulus, or bj a very strong nerve stimulus, wliicb lowers the irritability of 
the nerve-fibres. 
We do not find any rate of secretion beyond which an increase in rate fails to 
increase the percentage of salts in the saliva. The increment in the percentage of 
salts decreases with each equal successive increment in the rate of secretion. 
As a rule, in saliva obtained by injecting pilocarpin, the percentage of salts follows 
Heiuenhaim’s law. We take the exception to be due to the action of pilocarpin on 
the circulation, the blood-flow through the gland being less than normEdly accompanies 
the deofree of stimulation of the ffland-cells. 
The percentage of salts in saliva obtained by stimulating the sympathetic is higher 
than corresponds to its rate of secretion, the saliva obtained by stimulating the chorda 
being taken as a basis of comparison. 
Dyspnoea decreases the rate of secretion of saliva, 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 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 percentage of salts. Its after-effect is 
also much greater and lasts longer. Bleeding has a similar effect to dyspnoea and to 
clamping the carotid, and it causes a marked increase in the percentage of organic 
substance. 
Injection of dilute salt solution 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 substance 
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 compared 
with samples obtained before the injection that a discrepancy in the normal relation 
between percentage of salts and rate of secretion of water appears. 
Injection of sodium carbonate 2 per cent, also increases the rate of secretion of 
saliva; in this case the jiercentage of salts is about normal; the percentage of organic 
substance falls slightly only. 
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 on injection of strong salt solution 
into the blood which leaves the secretory power of the gland unaftected, 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 the strong salt 
solution an increase in the percentage of organic substance also takes place ; this and 
MDCCCLXXXIX.—B. 
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