502 THE SALIVARY GLANDS. 
In viscid saliva of the submaxillary gland of the clog, spheres or 
clumps of secreted substance are present. The number and the 
character of these vary broadly with the viscidity of the freshly-secreted 
saliva, and are, so far as I have seen, independent of the way in which 
the secretion is brought about. As sympathetic saliva is usually much 
more viscid than chorda saliva, it usually contains these constituents in 
much larger number. 1 
The spheres vary in appearance. In the more viscid specimens of 
saliva they are pale, have a very faint outline, and appear homogeneous 
(pale spheres). As a rule they are 2 to 4 /x in diameter, but 
larger and smaller ones occur. In the less viscid specimens of saliva 
some spheres like these are also found, but most are more watery- 
looking and are still paler (very pale spheres) : they vary much in size, 
but on an average are larger; they arc apparently the swollen forms of 
the ordinary pale spheres. There are also, especially in more watery 
saliva, spheres which differ from the preceding in having a fairly sharp 
outline (vacuolar spheres). In the more viscid forms of saliva, clumps 
occur as well as the pale spheres, and they are more numerous the more 
viscid the saliva. 
In saliva freshly secreted and freshly examined, the spheres and 
clumps may easily escape notice, even though they be present in 
hundreds in the field of the microscope. On standing they become 
more distinct, and they become obvious at the periphery of the drop, 
when they are still barely visihle in the centre. In sufficiently viscid 
saliva the spheres and clumps are much distorted at the edge of the 
drop, and in still more viscid saliva most of them are drawn out into 
elongated masses. 
Acetic acid, - 5 per cent, up to nearly glacial, makes the spheres and 
clumps very refractive and rather oily-looking. Glacial acetic acid 
causes them to swell up and become pale, and the clumps usually 
become vacuolated. Sodium hydrate causes them to swell up and 
disappear. 
When saliva containing spheres and clumps is allowed to stand, 
these bodies slowly settle, forming, as they do so, masses often of 
considerable size. The addition of an equal volume of 5 to 20 per cent, 
sodium chloride allows them to sink much more rapidly : they make 
a white, slightly adherent, but not viscid layer at the bottom of the 
vessel. 
On irrigating viscid saliva under a cover-slip, the fluid added mixes but 
slowly with the saliva, so that, instead of irrigating, it is sometimes better to 
mix a small drop of saliva with a small drop of the reagent, and to place a 
cover-slip on the mixture. AVater causes the spheres and clumps to disappear, 
but up to a certain point they can again be made visible by acetic acid ; 1 per 
cent. NaCl or Xa. 2 C0 3 makes the outlines of the bodies more distinct ; 1 per cent. 
osmic acid causes them to swell up and take a faint brown tint. Methylene- 
blue dissolved in Xa 2 C0 3 , 1 per cent, stains them, but as a rule not very quickly. 
Picrocarmine, safranin, and other reagents stain them slowly. When saliva 
is mixed with one to two volumes of dilute neutral or alkaline salts, dilute or 
1 Eekhard, Ztschr. f. rat. Med., 1866, Bel. xxviii. S. 120, found the sympathetic saliva 
from the parotid gland of the horse to be whitish and to contain fine particles. Schitf, 
"Lecons sur la digestion," p. 293, found the same with the first drops of saliva secreted 
rerlexly after a pause. The characters described were no doubt due to a precipitation of 
calcium salts in the saliva contained within the ducts. 
