500 MATER IA MEDIC A AND THERAPEUTICS. 



serious, however prolonged, is that it is accompanied by great 

 depression of the medulla, that is, of the respiration and circula- 

 tion, which, although sometimes to be turned to useful account, 

 may readily prove injurious or even highly dangerous. We thus 

 possess in narcotics a powerful means (1) of arresting perception, 

 (2) of inducing sleep, and (3) of soothing the great vital func- 

 tions, all of which may be of the greatest therapeutical service. 

 4. Sleep. We possess many methods of promoting or produc- 

 ing sleep, which we call hypnotics (virvos, sleep), or less properly 

 "narcotics." Thus we may be able to secure mental calm, or 

 the absence of noise and light, and to prevent or relieve pain or 

 other disturbing impressions, such as attend indigestion, heart 

 disease, and cough. Along with these indirect hypnotics, we 

 may employ direct hypnotics, which act on the convolutions, 

 either through the circulation or immediately upon the cells, 

 in either way reducing nervous metabolism. Amongst medi- 

 cinal hypnotics, the purest are perhaps the Bromides, which 

 appear to bring the brain into a condition which favours the 

 advent of natural sleep, rather than to induce it artificially, if 

 any such distinction can be drawn. Artificial sleep is readily 

 induced by the narcotics proper, including Chloral, Opium, 

 and Alcohol, as well as general anaesthetics, all of which produce 

 hypnotism amongst their other effects, and may be used for this 

 purpose. 



III. PATHOLOGICAL RELATIONS. 



We will now briefly consider some of the most common and 

 typical disturbances of the nervous system. The organic dis- 

 eases of this system are of great variety, including morbid states 

 of the vessels, syphilis, degenerations, etc., but it is only the 

 principal symptoms to which they give rise that will be 

 noticed here for the purpose of illustrating the applications of 

 the measures just discussed. 



1. Disturbances of Sensation: Pain. Pain is a familiar 

 disturbance of common sensibility of a peculiarly distressing 

 kind. As an expression of disease, whatever the tissue affected, 

 pain always originates in some nervous structure between and 

 including the periphery and the convolutions, but in every 

 instance it is referred to the periphery. When pain is severe, 

 it is accompanied by certain other phenomena, such as mental 

 depression and restlessness, sleeplessness, weakening of the 

 heart, indigestion, and other visceral disturbances. These may 

 be in part effects of the morbid condition on which the pain 

 also depends, but it is to be observed that pain is in itself a 

 powerful depressant of the centres and viscera, just like local 

 depressants of a pharmacodynamical nature. 



