ERRHINES 91 



by contractions and relaxations of the bronchial muscle 

 (unstriped). Afferent impressions conveyed in the vagus 

 fibres affect the respiratory centre, and at the same time 

 efferent (motor) impulses in the vagus efferent fibres may 

 determine a contraction of the muscle with lessening of the 

 calibre. Such a spasmodic contraction occurs in asthma. 

 It can be produced experimentally by drugs like pilocarpine 

 and physostigmine which stimulate vagal nerve-endings, or 

 by barium chloride acting directly on the muscle. The 

 vagal nerve-endings are depressed, and consequent relaxation 

 and dilatation of the tubes produced by atropine, hyoscya- 

 mine, and lobelia. The muscle is directly depressed and 

 relaxed by the nitrites. 



ERRHINES or sternutatories, when applied to the nostrils, 

 cause irritation, sneezing, and increased secretion. They in- 

 clude tobacco in a finely divided state, hellebore, ipecacuanha 

 euphorbium, and saponin. Errhines, although now seldom 

 used, were formerly prescribed to cause counter-irritation in 

 diseases of the eye and head, and to expel, by inducing 

 sneezing, foreign substances lodged in the nostrils, facial 

 sinuses, and respiratory passages. 



EXPECTORANTS increase and facilitate ths removal of 

 secretions from the air-passages. The healthy respiratory 

 mucous membrane is moistened and protected by a thin, 

 slightly adhesive solution of mucin, which is gradually moved 

 outwards by the cilia. Cold applied to the surface of the 

 body, dust and foreign particles, and micro-organisms, as in 

 cases of influenza, readily excite irritation of the respiratory 

 tract, and alter the amount and character of the mucus. 



While the irritated membrane is dry and vascular, as in the 

 earlier stages of catarrh and bronchitis, the breathing of 

 warm, moist air, diffused from a steam kettle, or nose-bag 

 containing steamed hay, beneficially dilates the congested 

 vessels, and promotes secretion. In such cases, and notably 

 in laryngitis, heat and moisture should also be applied 

 externally by means of poultices, or fomentation with flannel 

 or woollen waste wrung out of boiling water, covered with 

 thin waterproofing, and kept in place by a properly adjusted 

 hood. Further counter-irritation may subsequently be need- 

 ful. In the dry stage of inflammation of the respiratory 



