What do we do to ourselves when we smoke a cigar or pipe? In the first place, we stimulate, or increase the normal molecular activity of, the sympathetic system of nerves. By so doing we slightly increase the secretion of saliva, and of the gastric,[18] pancreatic, and intestinal juices. We accomplish these all-important secretory actions with a smaller discharge of nerve force: we economize nerve force in digestion. And by this we mean to say that we perform the work of digesting food just as well as before, and still have more of the co-ordinating and controlling nerve-power left with which to perform the other functions of life. Thus at the outset tobacco exhibits itself as an _economizer of life_. Such is the inevitable inference from its stimulant action on the sympathetic. From the distribution of the sympathetic fibres, we deem it a fair inference that the bile-secreting function of the liver is also facilitated; but of this there is less direct evidence.[19] We can now understand why a pipe or cigar dissipates the feeling of heaviness ensuing upon a dinner, or other hearty meal; and when we recollect how instant is the relief, we can form some notion of the amount of nerve-force which is thus liberated from the task of digestion. We are thus also reminded of the hygienic rule that smoking must be done after eating, and not, in ordinary cases, upon an empty stomach. If we smoke when the stomach is empty and quiescent, the stimulated secretion of the alimentary juices is physiologically wasteful; and, moreover, the much more rapid absorption of nicotine by the blood-vessels increases the liability to narcotic effects. It is upon this very principle that the same amount of wine may stimulate at dinner, but narcotize when taken in the forenoon. [18] "It is a positive fact that the gastric secretion can at any time be produced by simply stimulating the salivary glands with tobacco."--Lewes, _Physiology of Common Life_, vol. i. p. 192. The gastric secretion is also stimulated by the action of tobacco on the pneumogastric or eighth pair of nerves. [19] A possible means of testing this inference would be the judicious employment of smoking as a dietetic measure in cases of jaundice. This distressing disease occurs when the torpid liver secretes too little bile. The biliverdine, which would ordinarily be taken up to make bile, remains in the blood until, seeking egress through the sweat-glands, it colours the skin yellow. In the case of novices, however, great care would need to be taken; as unskilful smoking is very likely to induce narcosis.