288 PHILOSOPHICAL TRANSACTIONS. [ANNO 1798. 



must occasionally take place; but the difficulty will be much increased, when the 

 right side of the heart is more than ordinarily distended, in consequence of obstruc- 

 tion to the pulmonary circulation. Indeed it seems probable that such an obstruc- 

 tion, by occasioning a distended state of the right side of the heart, and thus im- 

 peding the circulation in the nutrient vessels of that organ, would as necessarily 

 occasion corresponding disease in it, as an obstruction to the circulation in the liver 

 occasions disease in the other abdominal viscera, were it not for some preventing 

 circumstances, which I now proceed to explain. 



Having been attentive to some very bad cases of pulmonary consumption, from 

 a desire to witness the effects of breathing medicated air in that complaint, I was 

 led to a more particular examination of the heart of those patients who died. In 

 these cases, I found, that by throwing common coarse waxen injection into the 

 arteries and veins of the heart, it readily flowed into the cavities of that organ; 

 and that the left ventricle was injected in the first place, and most completely. 

 When the ventricle was opened, and the effused injection removed, the foramina 

 Thebesii appeared both numerous and large, and distended with the different co- 

 loured wax which had been impelled into the coronary arteries and veins. On 8 

 comparative trials, made by injecting the vessels of hearts taken from subjects whose 

 lungs were either much diseased, or in a perfectly sound state; I found, that in the 

 former, common injection readily flowed, in the manner which I have described, 

 into all the cavities of the heart, but principally into the left ventricle; while, in 

 many of the latter, I could not impel the least quantity of such coarse injection 

 into that cavity. 



This difference in the facility with which the cavities of the heart can be injected 

 from its nutrient vessels, was observed by most anatomists, though they did not 

 advert to the circumstances on which it depended. Haller's recital of his own ob- 

 servations, and of those of others on this subject, so well explain the facts which 

 I have stated, that I shall take the liberty of quoting the passage, in order further 

 to illustrate and authenticate them. He says, " Si per arterias liquorem injeceris, 

 perinde in dextra auricala, sinuque et ventriculo dextro, et in sinu atque thalamo 

 sinistro guttulae exstillabunt; saepe quidem absque mora, alias difficilius, et non- 

 nunquam omnino, uti continuo dicemus, et mihi, et Senaco, et clarissimo Zinnio, 

 nihil exsudavit." — Elem. Physiol. Tom. 1, p. 382. 



As it seems right that the blood which had been distributed by the corouary 

 arteries, and which must have lost, in a greater or less degree, the properties of 

 arterial blood, should not be mixed with the arterial blood which is to be distributed 

 to every part of the body, but ought rather to be sent again to the lungs, in order 

 that it may re-acquire those properties; we therefore perceive why, in a natural state 

 of the heart, the principal foramina Thebesii are to be found in the right cavities of 

 that organ. However, as, even in a state of health, those cavities are liable to be 

 uncommonly distended, in consequence of muscular exertion sometimes forcing 

 the venous blood into the heart faster than it can be'transmitted through the lungs, 



