468 MATERIA MEDIC A AND THERAPEUTICS. 



the heart, partly directly, partly by reflexion through the 

 central nervous system of their impression on the gastric 

 mucosa. The mind is a powerful instrument for invigorating 

 the heart. Cheerfulness and encouragement may he more 

 useful to a patient than many drugs. Lastly, all measures 

 which lengthen the diastole (slow the heart) increase the 

 cardiac strength hy affording more time for rest. 



The intrinsic nervo-muscular apparatus may be depressed or 

 soothed by the opposite set of measures ; by a low coronary pres- 

 sure, the effect of low diet, purgatives, diuretics, and diaphoretics ; 

 by arresting reflex impulses by means of general, peripheral, 

 and central nervous sedatives, such as Opium, warmth, or 

 plasters applied to the prgecordium, and the general warm 

 bath; and by all measures which shorten the diastole, i.e., 

 increase the rate of the pulse. Lastly, we have a number of 

 drugs which are direct cardiac depressants, including Opium, 

 Diluted Hydrocyanic Acid, Aconite, Antimony, Potash, Chloro- 

 form, Chloral, Ergot, Veratria, Ipecacuanha and many more. 



The afferent nerves of the heart, which carry to the brain 

 the impressions of common sensibility originating in the cardiac 

 tissues, may be depressed by means of Opium, Chloral, Bella- 

 donna and its allies, and possibly by heat and cold. 



b. The terminations of the vagus in the heart may be stimu- 

 lated, and the cardiac action rendered less frequent, by Digitalis 

 and Scilla. The same part of the inhibitory mechanism may be 

 depressed, and the rate of the heat increased, by Belladonna, 

 Hyoscyamus, Stramonium, Amyl Nitrite, and large doses of 

 many drugs. These local measures act very powerfully. 



c. The cardiac centre in the medulla is readily stimulated by 

 certain drugs, such as Digitalis and Scilla, Ether, Alcohol and 

 Chloroform at first. Strychnia, and Belladonna ; and by many 

 peripheral nervous impressions, such as counter-irritation and 

 cold. On the other hand it can be depressed^ warm applications 

 to the surface, such as the hot bath, and by certain drugs, 

 including Chloroform and Alcohol after the first stage, Aconite, 

 Antimony, Opium, Chloral, Diluted Hydrocyanic Acid, Ipecacu- 

 anha, Nitrite of Amyl, Physostigma, and Conium. Our control 

 of the inhibitory action of the vagus at either extremity, that is, 

 of the frequency of the heart, is of much value from the power 

 which it affords us of influencing the cardiac nutrition and 

 strength, by lengthening or shortening the diastole or resting- 

 time of the ventricle. Thus it will be found that all cardiac 

 retarders are cardiac stimulants, whilst all cardiac accelerators 

 prove in the end to be cardiac depressants. 



In this connection muscular exercise and rest must be 

 mentioned as the most powerful and available of all the 



