_Trach._, trachea; _Ca._, carotid artery; _n. vag._, the vagus trunk; _n. rec._, the recurrent laryngeal; _sym._, the cervical sympathetic nerve ending in the inferior cervical ganglia, _gl. cerv. inf._ Two roots of the ganglion are shown--_rad._, the lower of the two accompanying the vertebral artery, _A. vert._, and being the one generally possessing accelerator properties; _gl. thor. pr._, the first thoracic ganglion. Its two branches, communicating with the cervical ganglion, surround the subclavian artery, forming the annulus of Vieussens. _sym. thor._, the thoracic sympathetic chain; _n. dep._, depressor nerve. This is joined in its course by a branch from the lower cervical ganglion, there being a small ganglion at their junction, from which proceed nerves to form a plexus over the arch of the aorta. It is this branch from the lower cervical ganglion which possesses accelerator properties, hence the course of the accelerator fibre is indicated in the figure by the arrows. (Modified from Foster's _Physiology_.)] All these operations paralyze the vaso-motor nerves by which, in health, the blood-vessels of the liver are kept in a state of tonic contraction; hence these vessels dilate when the nerves are cut. From the facts named we also learn the path of the glycogenic influence, which must be from the medulla oblongata into the spinal cord, thence by the filaments of the {197} sympathetic which accompany the vertebral artery into the lower cervical ganglion; thence through the annulus of Vieussens into the first dorsal ganglion; and thence through the prevertebral cord of the sympathetic, and branches not precisely determined, to the hepatic blood-vessels as shown by the dotted line in Fig. 3. [Illustration: FIG. 3. Diagram showing the course of the vaso-motor nerves of the liver, according to Cyon and Aladoff. These nerves are indicated by the dotted line which accompanies them: _a_, vaso-motor centre; _b_, trunk of the vagus; _c_, passage of the hepatic vaso-motor nerves from the cord along the vertebral artery; _d_, fibres going on each side of the subclavian artery and forming the annulus of Vieussens; _e_, first dorsal ganglion; _f_, ganglionated cord of the sympathetic; _g_, the spinal cord; _h_, the splanchnic nerves; _i_, coeliac ganglion, from which vaso-motor nerves pass to the hepatic and intestinal vessels; _k_, the lungs, to which fibres of the vagus are seen distributed; _l_, the liver; _m_, the intestine; _n_, the arch of the aorta.] I say, by branches of the sympathetic not precisely determined, because our power to produce artificial diabetes fails below the first thoracic ganglion; for section of the sympathetic between the tenth and twelfth ribs, and of the splanchnics, is not followed by glycosuria, although the vaso-motor nerves to the liver are known to pass through them.