Constituent parts of a complete innervation mechanism--The special duty of the peripheral terminations of afferent nerves--The specific qualities of nerve cells--Analogy between the innervation mechanism of the salivary glands and that of the deeper-lying glands of digestion--The exciting agencies of the nervous mechanism of the salivary glands; their particular properties--Differences between the exciting agencies of the different salivary glands--Discussion of the sham feeding experiment--Mechanical and chemical stimulation of the cavity of the mouth has no effect on the gastric glands--The experiment of Bidder and Schmidt relative to psychic excitation of the gastric secretion--Conditions for success in this experiment--The passionate longing for food--the appetite--alone brings on the secretory effect in the sham feeding experiment. GENTLEMEN,--As you have learned in the last lecture, and also in part have seen by direct experiment, the nervous system can influence the work of our glands in the most diverse ways. The vagus nerve, already burdened with many duties, has, in addition, proved itself to be an undoubted exciter of the gastric glands and of the pancreas. But we must also assign to the sympathetic nerve a similar _rôle_. This is a matter which cannot be doubted, so far as the pancreas is concerned, and is highly probable as regards the stomach. We also saw good reason for believing that these two nerves contained two different classes of fibres, secretory and trophic, a condition which had already been proved to exist by Heidenhain for the nerves of the salivary glands. As a hypothesis we might even have proceeded a step farther and have divided Heidenhain’s trophic nerves into separate classes of secretory fibres. Lastly, we advanced important experimental evidence to show the existence of special inhibitory fibres to the glands, and these fibres also run in the vagus, the list of whose functions seems almost interminable. We obtained these results by division and artificial excitation of the nerves which run to the glands. But when, how, and by what means these nerves are thrown into activity during the normal course of physiological events remains a question. In order to avoid repetition, and at the same time impart the utmost clearness to our representation, it may be useful to bring before your minds at once the plan of innervation of a given organ, all the more since this scheme is seldom completely followed out or adequately described in physiological text-books. Consequently, it is not borne in mind with sufficient precision by the majority of medical men.