568 REMEDIES IN BIIOXCIIITIS AND PHTHISIS. 



persons, on going out into the cold air, may cease to cough, hut 

 again begin to cough violently when they return from the cold 

 air into the warm room. The reason of this is that the cold air 

 has acted upon the congested vessels of the respiratory passages 

 in a somewhat similar way to what it does upon the vessels of 

 the face ; it causes them to contract, and the congestion being 

 thus diminished the cough is lessened. When the patient goes 

 into the warm room the face, which may have been pale while 

 he was exposed to cold, flushes up with the heat, the vessels of 

 the respiratory passages also become engorged, and the increased 

 congestion causes irritation, bringing on the cough. In other 

 cases, again, we notice that, just as the face becomes pale when 

 exposed to cold, it shortly afterwards becomes flushed, although 

 the application to cold continues. A person suffering from 

 bronchitis, on going into a cold room, will begin to cough 

 violently, the cold liere increasing instead of diminishing 

 congestion. 



The pulmonary capillaries have great contractile power. Ten 

 years ago I made some experiments, which I have not yet 

 published, on the subject {cf. antea, p. 334). I found that 

 on the application of cold to the lung of a frog, when 

 placed under the microscope, the capillaries would contract 

 to two-thirds of their former diameter. We have, however, 

 very few observations on the action of drugs upon the 

 pulmonary circulation, the difficulties in the operative pro- 

 cedure being very considerable. I have observed that mus- 

 carin appears to have a power of contrarting the pulmonary 

 vessels, and that this effect is abolished by atropia. I am 

 unaware, at present, of any other observations on the action of 

 drugs upon the pulmonary circulation. Circumstances have 

 prevented me from studying the recent researches on this 

 subject in the way I should have wished while drawing up this 

 paper. From its power of contracting the vessels in other 

 parts of the body, we should expect that digitalis would have a 

 similar action upon the lungs ; and we find, in looking over 

 Beasley's " Book of Prescriptions," that digitalis has been used 

 in pulmonary affections — as, for example, in the following 

 drauf^ht, employed by Sir A. Crichton in acute phthisis : lemon- 



