1823.] the Obstruction of the Blood in the Lungs. S13 



the heart, is a privation of its natural stimulus, arising from the 

 obstruction of the blood in the lungs. 



Among numerous phenomena observed in health and disease, 

 which I conceive to arise from an obstruction of the blood in the 

 lungs from a deficiency of pure atmospherical air, are the follow- 

 ing. Haemoptysis, in* my opinion, is generally the effect of an 

 accumulation of blood in the pulmonary artery, arising from a 

 deficiency of pure atmospherical air in the lungs to decarbonate 

 the blood, immediately on its being conveyed into that viscus* 

 The deficiency may arise from an interruption of the action of 

 the respiratory muscles, as from the immoderate use of the vocal 

 organs, or from inspiring rarified and impure air, or from the 

 over distension of the stomach, limiting the action of the dia- 

 phragm. Public speakers, singers, and performers on wind 

 instruments, are well-known to be the frequent victims of 

 haemoptysis. The enthusiastic orator, stimulated by the interest 

 of his subject, and proud of the approbation of his audience, 

 endeavours, by every exertion, to make the greatest impression 

 upon his hearers ; by so doing he interrupts his respiration, and 

 occasions a partial accumulation of blood in the pulmonary- 

 artery. If this interruption is often repeated, the minute 

 branches of the pulmonary artery must become more and more 

 dilated, as well as debilitated, and at last haemoptysis will suc- 

 ceed ; or, from habitual irritation, the foundation of a more 

 insidious disease will be laid, I mea.n tubercular consumption. If 

 the last conclusion be correct, we can account for the frequency 

 of tubercular consumption in countries subject to sudden vicissi- 

 tudes of the atmosphere. The consequence of sudden and 

 frequent changes of temperature, must be sudden and frequent 

 floods of blood, as it were, rushing into the lungs, especially 

 into the lungs of those who have a delicate and a highly sensible 

 constitution. The pulmonary arteries of open-chested persons 

 easily accommodate those frequent torrents, as the blood from 

 the capacity of their lungs is immediately exposed to the 

 influence of the atmosphere, and undergoes the necessary change 

 to admit it to proceed onwards without any delay. The pulmo- 

 nary arteries of narrow-chested persons, on the contrary, soon 

 feel the effects of a sudden increase in the circulating medium, 

 for their lungs are unable to supply the increase of blood imme- 

 diately with pure air, so as to enable it to proceed onwards with- 

 out delay ; therefore a temporary accumulation takes place in 

 the pulmonary artery, which must irritate its extreme termi- 

 nations. 



Now I flatter myself, that the cause of the phenomenon that 

 reserved the discovery of the circulation of the blood to modern 

 times, and to the honour of our country, has been disclosed, and 

 that no one for the future, however sceptip^il, will be able tq 



