SECRETION PHYSIOLOGY. 321 



Langley.-^^ Sections show the ducts plugged with a viscous 

 looking mass, and Langley suggests that the saliva is here too 

 thick to be expelled. In one experiment Langley found a dog's 

 parotid which secreted under the influence of the sympathetic 

 1.3 cc. Concerning this saliva Langley says :^" 



'' The saliva was of the most remarkable nature ; it formed a 

 thick jelly-like mass ; if allowed to collect at all in the canula 

 it could be drawn out as a continuous clot. During the experi- 

 ment the duct was frequently emptied by pressure to prevent 

 its being stopped up." The saliva contained 7.8 ^ of organic 

 solids. We can, moreover, artificially alter the fluidity of the 

 saliva in the ducts, rendering it more dilute, by the action of the 

 chorda tympani or pilocarpine. In such cases, as we have seen 

 in speaking of the augmented secretion, sympathetic saliva is 

 almost as thin as chorda saliva. By long stimulation of the 

 chorda, moreover, we may exhaust the soluble constituents of 

 the gland. In such cases it may be presumed that the gland 

 saliva is thinner than normal. It is known that under such cir- 

 cumstances the sympathetic saliva may fall within the limits of 

 density of chorda saliva.* A similar change occurs in paralytic 

 secretions following division of the chorda. The gland then 

 secretes a very thin saliva, and sections show the cells practic- 

 ally exhausted of their mucous. The sympathetic in these 

 causes a very abundant and very watery secretion. 



We may obtain still further evidence of the character of the 

 saliva normally present in the ducts of the resting gland by a 

 sudden, strong stimulation of the chorda tympani. The rapid 

 inflow of fluid from the capillaries about the alveoli, taking place 

 under the influence of that nerve, drives out the saliva in the 

 ducts before it has time to become diluted. If we examine this 

 saliva first appearing on chorda stimulation we find it in all re- 

 spects typical sympathetic saliva. From this Schiff concluded! 

 that sympathetic saliva was nothing more than the saliva nor- 

 mally present in the ducts, formed during glandular rest. 



* Heidenhain, Studien aus Breslau, IV, 1868. After long sympathetic stimula- 

 tions the saliva becomes " diinnflussig, hell, und dadurch dem chorda Speichel 

 ganz und gar ahnlich." 



t Schiff". LeQons sur la Digestion. Tome I., p. 296, 1867 ; also p. 304. 



