ON THE SECRETION OF SALIVA. 
151 
At the same time, it may bo pointed out that Novi observed an increase above normal in the percentage 
of chlorine in saliva in thi'ee cases only, and these only slightly exceed the maximum known to occur in 
normal saliva. The maximum found by Wertiier in normal saliva is ‘352 per cent.; in the thi’ee cases of 
Novi, mentioned above, the percentages of chlorine are '360, '363, '382, and Novi mentions that the 
error in estimation of the chlorine may be as much as ’03 per cent. 
Novi also found that, when the chlorine in serum was increased to ’7 per cent., no 
more saliva could be obtained from the gland. His method of obtaining saliva was to 
place dilute acids or weak ammonia in the mouth, and so to set up a secretion reflexly. 
In our Experiments 10 and 11, the injection of strong salt solution distinctly lowers 
the amount of saliva that could be obtained from the gland by stimulating the 
chorda tympani and by pilocarpin, and, when injected in sufficient amount, prevented 
all secretion from taking place. Hence, it seems to us probable that, if the injection 
of salts can lead to an increase in the percentage of salts in the saliva above normal, 
the amount of salts injected must be regulated with great nicety. 
Some Remarks on the Theory of Secretory Nerves. 
We do not propose to discuss the question whether there is more than one kind 
of secretory nerve ; but there are some facts in the foregoing experiments bearing on 
the question which we cannot leave without mention. 
The most striking of these is the effect of bleeding in Experiment 8. The loss of 
blood causes an increase in the percento.ge of organic substance in the saliva.^ This 
tends to show that with a given stimulus the percentage of organic substance 
increases as the blood-flow through the gland decreases. Further, the actual rate of 
secretion of organic substance is somewhat decree,sed by loss of blood, and this may 
be fairly interpreted as meaning that with a lessened blood supply the gland-cells 
become less irritable. Lastly, loss of blood increases the percentage of salts much less 
than it increases the percentage of organic substance; that is to say, the secretion of 
salts is much less affected by the strength of stimulus than the secretion of oi’ganic 
substance. 
Hence, it would appear that with a given stimulus to the gland-cells a decrease in 
Since writing this we have met with an observation o£ Zerner (‘Medizinische Jahrbiicher,’ 1887, 
p. 534) bearing on the secretion of organic substance. He finds in the Dog that, after lowering the 
blood pressure by section of the cervical spinal cord, the more slowly secreted sub-maxillary saliva, 
obtained by stimulating the chorda tympani, has a higher percentage of organic substance than the more 
rapidly secreted saliva, similarly obtained under normal conditions. Two expei’iinents are given. One of 
these is inconclusive, since the sympathetic was stimulated before obtaining the second sample of chorda 
saliva, and this, as Heidenhain has shown, is sufficient to increase the percentage of organic substance. 
The other experiment, although more satisfactory, is not entirely so, for the chorda tympani was stimu¬ 
lated with strong shocks between the time of collecting the two samples of saliva analysed.—Feb. 6,1889. 
