DIGESTION. 233 



ceeds with it for a short distance, and then passes along the submaxillary 

 gland duct (Fig. 170, sm. d.), to which it is distributed, giving branches 

 to the submaxillary ganglion (Fig. 170, sm. gl.), and sending others to 

 terminate in the superficial muscle of the tongue. If this nerve be exposed 

 and divided anywhere in its course from its exit from the skull to the 

 gland, the secretion, if the gland be in action, is arrested, and no stimu- 

 lation either of the lingual or of the glosso-pharyngeal will produce a flow 

 of saliva. But if the peripheral end of the divided nerve be stimulated, 

 an abundant secretion of saliva ensues, and the blood supply is enormously 



FIG. 170. Diagrammatic representation of the submaxillary gland of the dog with its nerves and 

 blood-vessels. (This is not intended to illustrate the exact anatomical relations of the several struct- 

 ures.) 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.L, n.l'., the lingual or gustatory nerve; ch. t., ch. '., 

 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.. submaxillary ganglion 

 with its roots; n. /., the lingual nerve proceeding to the tongue; a. car., the carotid artery, two 

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

 .S//1.. the anterior and posterior veins from the gland ending in v. j., the jugular vein; v. sym., the con- 

 joined 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 glandular 

 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 lin- 

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



increased, the arteries being dilated. The veins even pulsate, and the 

 blood contained within them is more arterial than venous in character. 



When, on the other hand, the stimulus is applied to the sympathetic 

 filaments (mere division producing no apparent effect), the arteries con- 

 tract, and the blood stream is in consequence much diminished; and from 

 the veins, when opened, there escapes only a sluggish stream of dark 

 blood. The saliva, instead of being abundant and watery, becomes scanty 

 and tenacious. If both chorda tympani and sympathetic branches be di- 

 vided, the gland, released from nervous control, secretes continuously and 

 abundantly (paralytic) secretion. 



The abundant secretion of saliva, which follows stimulation of the 



