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452 DIGESTION.
zymogens, besides extractive bodies, leucine, purine bases, and mineral
substances.
The occurrence of a mucinogen has not been proved. On the complete removal
of all mucin E. Holmgren 1
found no mucinogen in the submaxillary gland of
the ox, but a mucin-like gluconucleoproteid.
1 he saliva is a mixture of the secretion of the above-mentioned groups
of glands; therefore it is proper that a study be made of each of the dif-
ferent secretions by itself and then of the mixed saliva.
The submaxillary saliva in man may be easily collected by intro-
ducing a canula through the papillary opening into Wharton’s duct.
The submaxillary saliva has not always the same composition or
properties; this depends essentially, as shown by experiments on animals,
upon the conditions under which the secretion takes place. That is to
say, the secretion is partly dependent on the cerebral system, through
the facial fibers in the chorda tympani, and partly on the sympathetic
nervous system, through the fibers entering the vessels in the gland. In
consequence of this dependence the two distinct varieties of submaxillary
secretion are distinguished as chorda- and sympathetic saliva. A third
kind of saliva, the so-called paralytic saliva, is secreted after poisoning
with curare or after the severing of the glandular nerves.
The difference between chorda- and sympathetic saliva (in dogs)
consists chiefly in their quantitative constitution; the less abundant
sympathetic saliva is more viscous and richer in solids, especially in
mucin, than the more abundant chorda-saliva. The specific gravity of
the chorda-saliva of the dog is 1.0039-1.0056, and contains 12-14 p. m.
solids (Eckhard 2
) . The sympathetic has a specific gravity of 1 .0075-1 .018,
with 16-28 p. m. solids. The freezing-point of the chorda-saliva obtained
from dogs on electric stimulation varies, according to Nolf,3
between
A = -0.193° and -0.396°, with a content of 3.3-6.5 p. m. salts and 4.1-
11.5 p. m. organic substances. The osmotic pressure is on am average a
little higher than one-half the osmotic pressure of the blood-serum. The
spontaneously secreted submaxillary saliva is ordinarily somewhat diluted.
On changing the osmotic pressure of the blood the osmotic pressure
of the saliva, according to Jappelli,4
changes in the same direction.
According to Demoor, Locke’s solution with some dog serum is well
suited by transfusion to keep the submaxillary gland of the dog in
activity, while ox serum is unsuited.5
The gases of the chorda-saliva
1
Upsala Lakaref. F6rb. (N. F.), 2; also Maly’s Jahresber., 27.
2
Cited from Kiihne’a Lebrb. d. physiol. Chem., 7.
<<<-. Maly’s Jahresber., 81, 494.
4
.Jappelli, ibid., 48 and 51.
5
Arch, intern, de Physiol., 10 (1911).
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