INFLUENCE OF NERVES ON THE SITBMAXILLARY GLAND 307 



saliva ensues for a short time, although the blood supply is necessarily absent. 

 These experiments serve to prove that the chorda contains two sets of nerve 

 fibers, one set, vaso-dilator, which, when stimulated, act upon a local vaso- 

 motor center for regulating the blood supply, inhibiting its action, and causing 

 the vessels to dilate, and so producing an increased supply of blood to the 

 gland; while another set, which are paralyzed by injection of atropine, directly 

 stimulate the cells themselves to activity, whereby the cells secrete and dis- 

 charge the constituents of the saliva which they produce, the secretory nerves. 

 These latter fibers very possibly terminate on the salivary cells themselves. 

 If, on the other hand, the sympathetic fibers be divided, stimulation of the 



FIG. 250. Diagrammatic Representation of the Submaxillary Gland of the Dog with its Nerves 

 and Blood-vessels. (This is not intended to illustrate the exaet anatomical relations of the several 

 structures.) sm. gld.. The submaxillary gland into the duct (sm. d.) of which a cannula has been 

 tied. The sublingual gland and duct are not shown, n. I., n. I'., The lingual or gustatory nerve; 

 ch. t., ch. t'., the chorda tympani proceeding from the facial nerve, becoming conjoined with the 

 lingual at n. I'., and afterward diverging and passing to the gland along the duct; sm. gl., submax- 

 illary ganglion with its roots; n. L, the lingual nerve proceeding to the tongue; a. car., the carotid ar- 

 tery, two branches of which, a. sm. a. and r. sm.p., pass to tljie anterior and posterior parts of the gland; 

 v. sm., the anterior and posterior veins from the gland ending in v. /., the jugular vein; v. sym., the 

 conjoined vagus and sympathetic trunks; gl. cer. s., the superior-cervical ganglion, two branches of 

 which forming a plexus, a. /., over the facial artery, are distributed, n. sym. sm., along the two glan- 

 dular arteries to the anterior and posterior portion of the gland. The arrows indicate the direction 

 taken by the nervous impulses; during reflex stimulations of the gland they ascend to the brain 

 by the lingual and descend by the chorda tympani. (M. Foster.) 



tongue by sapid substances, or electrical stimulation of the trunk of the lin- 

 gual or of the glosso-pharyngeal, continues to produce a flow of saliva. From 

 these experiments it is evident that the chorda-tympani nerve is the principal 

 nerve through which efferent impulses proceed from the center to excite the 

 secretion of this gland. 



The sympathetic nerve also contains two sets of fibers, vaso-constrictor 

 and secretory. But the flow of saliva, upon stimulating the sympathetic, is 

 scanty, and the saliva itself viscid. At the same time the vessels of the gland 



