316 



the blood brought to the left auricle is formed of that portion which 

 comes direct from the air-cells, and that which, after leaving the 

 air-cells, has undergone the further process of distribution on the 

 bronchial membi'ane, and has been the source from whence the 

 epithelium and the bronchial mucus have been derived, and may 

 therefore be considered as somewhat altered in character from that 

 which, coming direct from the air-cells, has not been exposed to 

 such changes. 



5thly. It is possible to inject entirely the pulmonary artery and 

 veins, without injecting the bronchial arterj* or veins ; and it is also 

 possible thoroughly to inject the latter Vvnthout at all injecting the 

 former ; and when that is the case, i. e. the (so called) bronchial 

 arteries are injected while the pulmonary vessels are empty, it will 

 be found that the bronchial membrane is wholly uninjected, however 

 perfectly the (so called) bronchial vessels may have been filled. 



6thly. By injecting the lung through the pulmonary veins, the 

 bronchial membrane becomes thoroughly injected, even before the 

 air-cells are so ; on the contrary, when the pulmonar}' artery is alone 

 injected, the air-cells become injected long before the liquid reaches 

 the bronchial membrane. In neither of these cases are the bronchial 

 arteries, i. e. those derived from the aorta or veins which correspond 

 to them, in the slightest degree injected. 



7thly. The bronchial arteries, which are injected by filling the 

 aorta, terminate in veins, which ramify in the subpleural cellular 

 tissue ; the greater part of these, after ramifying on the surface of the 

 lung beneath the pleura, pass along the broad band of pleura, which 

 extends from the peduncle of the lung to the posterior mediastinum, 

 and encloses the root of the lung, and v^iiich may be called the 

 mesopleura, and the veins then empty them.selves into the oesophageal 

 veins and other veins in the posterior mediastinum. It is probable 

 also that some terminate in the azygos veins, the jugular veins, the 

 diaphragmatic veins, and the vense cavae ; in short, wherever they 

 can meet with a systemic vein situated conveniently ; but they form 

 no sort of communication with the pulmonary veins, either in their 

 caj^illaries or their larger trunks. 



8thly. It is found that the coats of the lymphatic vessels of the 

 lung are supplied by blood-vessels which are derived fi*om the au'- 

 cells, and which terminate in the pulmonary veins, and the distribu- 

 tion of the blood-vessels on the coats of the lymphatics bears a strong 

 resemblance to those distributed on the bronchial membrane. 



The author then describes his apparatus for injection ; the sub- 

 jects injected ; and the drawings which accompany his communica- 

 tion. In conclusion he states, that sufficient has been adduced to 

 confute the opinion that there is one set of vessels for the nutrition 

 of the lung in its ordinary acceptation, and another for the respira- 

 tory function. Without doubt the bronchial (so-called) vessels and 

 the pulmonary are distinct, both as to their distribution and func- 

 tions ; the one being for the purposes of breathing, while the other 

 solely supplies the cellular tissue of the organ. 



