SEDATIVES IN COUGH. 565 



of about one-sixth of a grain of morphia to two grains of 

 starch. This mixture is introduced into a glass tube, of a 

 proper shape, and is blown down the throat at the instant that 

 the patient takes a deep inspiration. The powder is thus dis- 

 tril)uted over the interior of the larynx, and exerts its local 

 sedative influence upon the irritated surface, as well as a general 

 sedative effect upon the central nervous system after its absorp- 

 tion. 



This brings us to the second mode in which sedatives relieve 

 cough. After their absorption into the blood, in whatever 

 manner they may have been applied, they are carried to the 

 medulla, and there lessen the excitability of the nerve centre 

 through which the reflex act of coughing is produced. In large 

 doses their sedative effect may be so great as to endanger life, 

 and the caution is given in every text-book, and by every 

 teacher, that respiratory sedatives such as opium should be 

 carefully administered to persons suffering from bronchitis with 

 profuse expectoration, lest the irritability of the medulla should 

 be so far diminished that it will no longer respond even to a 

 powerful stimulus from the lungs, and the secretion may conse- 

 quently go on accumulating until when the patient awakes the 

 respiratory passages are so clogged with mucus that no effort 

 which he can make is sufficient to clear them, and he dies of 

 suffocation. By administering them in smaller quantities, how- 

 ever, the effect of respiratory sedatives may be graduated so as 

 to diminish cough without any risk of causing death, and their 

 effect would be exceedingly beneficial if they acted only upon 

 the respiratory centre. Unluckily, however, this is not the case, 

 and the most powerful of all — viz., opium — not only influences 

 the respiration, but the digestion. It diminishes the cough, 

 but sometimes, also, it diminishes the appetite, and may inter- 

 fere with the proper action of the bowels. When this is the 

 case, we are obliged carefully to steer between two dangers: 

 (1) the injurious effects of the cough itself, and (2) the injurious 

 effect of disturbed digestion. If we leave the cough alone, it 

 exhausts the patient, for the muscular exertion involved in a 

 violent fit of coughing is very considerable indeed, and the 

 muscular effort exerted by a patient with a bad cough during 



