502 THE SALIVARY GLANDS. 



In viscid saliva of the submaxillary gland of the dog, 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 ^ 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 are 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 visible 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. Water 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 Na 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 Na 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 Eckhard, Ztschr. f. rat. Med., 1866, Bd. xxviii. S. 120. found the sympathetic saliva 

 from the parotid gland of the horse to be whitish and to contain fine particles. Scliiff, 

 "Le9ons sur la digestion," p. 293, found the same with the first drops of saliva secreted 

 reflexly after a pause. The characters described were no doubt due to a precipitation of 

 calcium salts in the saliva contained within the ducts. 



