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When a bronchial artery, as it enters the substance of the lung, is 

 injected, the vessels of the bronchial tubes become filled both those 

 of the mucous membrane and of the deeper portions and the fluid 

 finds its way into the pulmonary veins. If the injection be con- 

 tinued, it is easy to inject the pulmonary plexus through the medium 

 of the bronchial arteries ; and injection is often found in the branches 

 of the pulmonary arteries. 



In injecting a bronchial artery in the human subject, I have always 

 found that part of the bronchial tubes nearest the point of insertion 

 of the injection pipe more fully injected, both as regards the mucous 

 membrane and the deeper structures, than the parts situated towards 

 the extremity of the tubes. I have found the larger branches injected 

 nearly to the end of the tubes, but not the fine vessels of the mucous 

 membrane. This seems to me to be due to the fact, that throughout 

 the entire extent of the tubes there is so free a communication be- 

 tween the bronchial vessels and the pulmonary veins, that the fluid 

 finds its way into the latter more readily than into the fine plexus of 

 the extreme tubes. 



The Bronchial Veins. The examination of a large number of 

 specimens, both of the lungs of man and the lower animals, and the 

 injection of the vena azygos on several occasions, have not enabled 

 me to find the so-called deep bronchial veins, as vena comites of the 

 bronchial arteries. I have always found a small vein or veins, gene- 

 rally a single one, situated at the posterior aspect of the bronchus, 

 and terminating, as shown by the injection, in the structures of 

 bronchus, lower part of trachea, and glands at the root of the 

 lung, but not passing along the bronchial tubes within the lung, and 

 therefore being in no way concerned in returning the blood distri- 

 buted to those parts by the bronchial arteries. 



A piece of human lung well injected by the bronchial artery, ex- 

 hibits on the mucous membrane of the bronchial tubes, a fine plexus 

 of vessels, taking for the most part a longitudinal direction ; under 

 these other vessels are found, which run transverselv beneath the 

 elastic tissue, in the direction of the muscular fibres ; these deeper 

 vessels are larger than the superficial ones ; there is a distinct com- 

 munication between the two sets. 



I now pass to consider in what manner, and where t the communi- 



