INFLUENCE OF NERVOUS SYSTEM ON DIGESTIVE GLANDS 391 



same properties as the antitrypsin in the intestinal worms (Hamill). 

 This explains the resistance of blood-serum to the digestive action 

 of trypsin. In addition to this body, which hinders the action of 

 fully-formed trypsin, and has no effect upon enterokinase, the 

 serum of some animals contains an antikinase i.e., a substance 

 which hinders the action, not of trypsin, but of enterokinase, pre- 

 venting it from activating the trypsinogen into trypsin. 



SECTION V. THE INFLUENCE OF THE NERVOUS SYSTEM 

 ON THE DIGESTIVE GLANDS. 



The Influence of Nerves on the Salivary Glands. All the salivary 

 glands have a double nerve-supply, from the medulla oblongata 

 through some of the cranial nerves, and from the spinal cord through 

 the cervical sympathetic (Fig. 160). 



In the dog the chorda tympani branch of the facial nerve carries the 

 cranial supply of the sublingual and submaxillary glands. It joins the 

 lingual branch of the fifth nerve, runs in company with it for a little 

 way, and then, breaking off, after giving some fibres to the lingual, 

 passes, as the chorda tympani proper, along Wharton's duct to the 

 submaxillary gland. In the hilus of this gland most of its fibres break 

 up into fibrils around nerve-cells situated there, and lose their medulla 

 in doing so. A few fibres terminate in a similar manner before entering 

 the hilus, and a few deeper in the gland. The nervous path is continued 

 by the axis-cylinder processes (p. 851) of these nerve-cells, which, 

 passing in as non-medullated fibres, end in a plexus on the basement 

 membrane of the alveoli. From the plexus fibrils run in among the 

 gland-cells, but do not seem to penetrate them. The lingual, the 

 chorda tympani proper, and Wharton's duct form the sides of what is 

 called the chordo-lingual triangle. Within this triangle are situated 

 many ganglion cells, a special accumulation of which has received the 

 name of the submaxillary ganglion. This, however, should rather be 

 called the sublingual ganglion, since its cells, as well as the others in the 

 chordo-lingual triangle, are the cells of origin of axons which proceed 

 as non-medullated fibres to the sublingual gland. The sublingual gland 

 receives its cerebral fibres partly from branches given off from the 

 lingual in the chordo-lingual triangle after the chorda tympani proper 

 has separated from it, and ending around the nerve-cells within that 

 triangle, partly from the chorda itself in the terminal portion of its 

 course. These statements rest on anatomical and physiological evi- 

 dence. The latter we shall return to. 



The cerebral fibres for the parotid (in the dog) pass from the tympanic 

 branch of the glosso-pharyngeal (Jacobson's nerve) through connecting 

 filaments to the small superficial petrosal branch of the facial, with 

 this nerve to the otic ganglion, and thence by the auriculo-temporal 

 branch of the fifth to the gland. 



The sympathetic fibres for all the salivary glands appear to arise from 

 nerve-cells in the upper dorsal portion of the spinal cord. Issuing 

 from the cord in the anterior roots of the upper thoracic nerves (first to 

 fifth, but mainly second thoracic for the submaxillary), they enter the 

 sympathetic chain, in which they run up to the superior cervical 

 ganglion. Here they break up into terminal twigs, and thus come into 



