On Muscular Motion and Animal Spirits 297 



muscles, is liable to convulsive movements, and its 

 palpitation seems sometimes to be referable to these. 



As to the asthmatic paroxysm, to which the afore- 

 said patient was subject after any more violent 

 motion, that seems to have arisen thus, that the 

 blood which, on account of the contraction of the 

 muscles, reached the right ventricle of the heart in 

 a fuller stream, could not freely pass through the 

 lungs and make its way to the left ventricle of the 

 heart. But I would not have this so understood as 

 if I supposed that the blood detained in the lungs so 

 stuffed them up as to prevent the entrance of air 

 into them ; for, however the blood-vessels of the 

 lungs are distended with blood or any other liquid, 

 the lungs themselves do not swell up ; but all the 

 same they do enlarge when air is blown into them, 

 and quite promptly subside when the air is expelled, 

 as may be tested on the body of any animal by 

 passing blood or any other liquid into the pulmonary 

 vein after ligature of the pulmonary artery, and then 

 inflating the lungs by means of bellows attached to 

 the trachea. And in fact if the blood stagnate in the 

 pulmonary vessels, the patient is affected just as if 

 the respiration were suppressed ; for there are two 

 things specially effected by the respiration : — 



First, that the mass of the blood should be led 

 through the lungs into the left ventricle of the heart 

 (yet that takes place not so much for the motion of 

 the lungs, as that the blood may ferment with the 

 nitro-aerial particles mixed with it by respiration, 

 and be protected from coagulation, as has been shown 

 above). Wherefore, if the blood for any reason 

 should stagnate in the lungs, as happened in the 

 case mentioned, the patient at once becomes breathless, 

 and suffocation is nearly produced. 



