CAUSES OF COUGH. 567 



and clilorofurm to lessen the excitability of the respiratory- 

 centre ; we find glycerine, which will tend to retain the seda- 

 tives for a longer time in contact with the back of the throat, 

 and will also act to some extent as a nutrient. We have com- 

 bined with these nitric acid and infusion of cascarilla or of 

 quassia, which have so-called tonic (?) action upon the stomach. 

 In what this effect precisely consists we cannot at present say, 

 but we may imagine that it will in some way partially counter- 

 act the effects of the congestion which the cough produces, and 

 at the same time we know that they have the power of exciting 

 appetite, and they will thus in a great measure counterbalance 

 the injurious effects of the morphia upon digestion. Nor is this 

 all. The nitric acid, as I shall shortly have to mention, has a 

 very definite effect indeed upon the secretion in the lungs 

 themselves ; and this brings us to the consideration of another 

 part of our subject — viz., the effect of drugs upon the secretion 

 and nutrition of the lungs, by which they tend to restore the 

 healthy condition of the bronchial and pulmonary tissues, and 

 thus diminish coughing. 



First of all, then, we must consider those drugs which lessen 

 congestion. If a person, hastily eating or drinking, gets a 

 crumb of bread or a drop of fluid down the larynx, or into the 

 wrong throat, as it is termed, he suddenly begins to cough 

 violently, and the cough continues until the source of irritation 

 has been removed. If the irritation has been violent he may 

 give a few coughs after the crumb has been conghed up, although 

 the primary source of irritation — namely, the crumb — has dis- 

 appeared ; but the congestion which it occasions still remains 

 for a short time, and acts as an irritant. If a person suffering 

 from disease of the mitral valve makes any sudden exertion he 

 is very likely to bring on a cough, which, however, quickly 

 subsides after a short rest. The cough here is not due to 

 inflammation of the mucous membrane, but simply to conges- 

 tion, and when the congestion disappears the irritation goes 

 with it. In cases where we have inflammation of the respira- 

 tory vesseb actually present, as in persons suffering from 

 bronchitis, the congested condition of the membrane is a source 

 of considerable irritation, and we frequently notice that such 



