SECRETION PHYSIOLOGY. . 325 



the above. (Breslau Studien, p. 69, IV.) In taking the- secre- 

 tory pressure of the dog's submaxillary he stimulated the 

 chorda until the pressure in the ducts was 271 mm. Hg. On 

 ceasing stimulation the manometer gradually fell. On stimula- 

 ting the synipatlictic the siiikiiig became niueJi slcnuer, and the ma- 

 nometer remained stationary at 160 mm. On breaking the 

 stimulation the manometer sank gradually to 100. On stimu- 

 lating the sympathetic it rose to 107, and on chorda stimulation 

 to 271. It gradually fell during following sympathetic stimula- 

 tion, bnt on breaking the stimulation it fell i^'ith striking rapidity 

 (Auftalig beschleunigtes Sinken). Heidenhain thus records for 

 the dog's submaxillary the same sudden back flow on breaking 

 the stimulation of the sympathetic as Eckhard and von Wittich 

 describe in the sheep. 



Paradoxical though it may seem, the experiments just quoted 

 of von Wittich and Eckhard have been cited b)" Heidenhain as 

 conclusive evidence that the sympathetic does not simply drive 

 out the secretion already in the gland. And it is this con- 

 viction which led Heidenhain, in the discussion of all experi- 

 ments involving the sympathetic, to ignore the possibility of its 

 having such an action. Heidenhain believed von Wittich was 

 right in contending that the failure of the manometer to return 

 to its former level on breaking stimulation proved that the 

 amount of saliva in the gland had been increased. It will be 

 instructive to consider von Wittich's explanation of the phe- 

 nomena of this secretion, von Wittich"'' suggests that the back 

 flow of the saliva is due to the saliva being pushed back into the 

 cells. Let us examine this more closely. von Wittich and 

 Heidenhain assumed that the cells, on stimulation, discharge 

 their stored products into the lumen. Such a process, it need 

 hardly be said, would lead to no secretion from the ducts, as 

 the bulk of the cell would diminish to just the extent that the 

 bulk of fluid in the ducts increases. Hence the bulk of cell 

 plus liquid would remain unaltered. W^e must, therefore, make 

 either one of two farther assumptions : First, that the alveoli are 

 greatly distended owing to the turgor of the cells. Stimulation 

 of the nerv^e might conceivably diminish the resisting power of 



Anxals N. Y. Acad. Sci., XI, September 13, 1898 — 22. 



