SUBSTANCES SECRETED IN SALIVA. 503 
strong acids, the spheres and clumps gradually disappear. In strong solutions 
of neutral salts (e.g. 20 per cent, sodium chloride), they may be kept for months 
at any rate. Strong alcohol and mercuric chloride cause them to shrink and 
make them irregularly granular. Flemming's fluid turns many of them into 
vacuolated spheres, with sharp outline and a few distinct small granules. No 
mucous cells are seen in saliva after treatment with any of these reagents. 
In the submaxillary saliva of the cat, vacuolar and pale spheres are found, 
but not the larger clumps. 
Microscopical constituents in saliva have been described by Eckhard, 
Kuhne, and Heidenhain. The account I have given above differs in several 
points from theirs. 
The most obvious view to take of these microscopical constituents 
of saliva is, I think, that some of the mucous granules are turned bodily 
out of the alveolar cells, 1 the fluid passing through the cells being 
insufficient to dissolve them; and that by swelling up or massing 
together they make the various forms of spheres and clumps which are 
seen. But although the mucous granules behave with some reagents 
very much as do the small spheres of saliva, and have in some states 
very much the same appearance, their behaviour with acetic acid is 
strikingly different. The mucous granules, on treatment with dilute 
acetic acid, swell up and burst like bubbles ; 2 the spheres in saliva, as we 
have seen, become refractive and obvious. Although it is possible that 
this difference may depend on differences in the surrounding fluids, it is 
sufficient to prevent more than a provisional acceptance of the view 
that the spheres of saliva are simply undissolved mucous granules. 
Substances which are or which may be secreted ix Saliva. 3 
In saliva obtained from mucous glands, the chief organic constituent 
is naturally mucin. Little is known with certainty of the varieties of 
mucin which exist. In mucous saliva, whilst most of the mucin is 
precipitated by acetic acid as a stringy lump, there is not infrequently 
a portion which is precipitated in fine particles, these making the fluid 
cloudy. A small quantity of proteid is also present, probably belonging 
to the class of globulins. 
In saliva obtained from albuminous glands the proteid constituents 
are globulin (or a body allied to globulin), alkali albuminate, and a 
small amount of serum albumin. 4 
In typical mucous saliva, diastatic ferment is either absent, or 
present in mere traces ; in saliva from albuminous glands, the amount 
of diastatic ferment is variable and independent of the percentage of 
proteid, but in the saliva of any one gland the diastatic action increases 
w T ith the percentage of proteid present. 
The salts are, so far as is known, the same in mucous and in 
albuminous saliva, although their percentage amount varies considerably 
in the saliva obtained from different glands. The bases found are 
sodium, potassium, calcium, and magnesium ; the acids are hydrochloric 
acid, carbonic acid, phosphoric acid, and sulphuric acid. Sodium 
chloride is by far the largest constituent ; after this comes usually 
1 Langley, Proc. Roy. Soc. London, 18S6, vol. xi. p. 202. 
2 Langley, Journ. Physiol., Cambridge and London, 1889, vol. x. p. 433. 
3 See also article on " Composition of Saliva," p. 342. 
4 Kuhne, " Lehrbueh. d. Physiol.," 1866. 
