ASD TRETR YXTSCTIOSS. 1^ 



qTiadmpeds, the paiis of the lung are separated sj ~~:ji 

 thai there seem to t-r r^: -^:^^=- -::i:i^:'^- ": i ii^le 

 trachea.* 



The fact that the lungs comnnziicaie with a =:^".e 

 trachea caiised Ari?:-:T> :■: =T-^ii: :: the hmg. nyi the lyings. 

 of an animal. Thir :_ : :-; ; : " t : irihing the Inngs is scme- 

 what similar to his me :j.: i :: . " " ' , ' 



some fishes. H's des:r': " :■.-;;..__. . _ ._ . : 



the hnman lungs is - ■ : ;::r7 7i:f -^i^^- — ^azi. 



are distinctly r:-^ -": : ._t .tIT i^iiig hi= r^: mi liie 

 right Inng thif 



He says - - :^- - 



cartiIagino"c= f _::-_. 1 __ : - _. i:^_:i. r:i:li .,? 



contracting to a point, sni Lrom thezi ize i^r:: . ■ :_e 

 through all parts of the liing. and these pprfpyar :^ - it 

 branching, become sm.aller and smaller.-^ 



This description read.s accnrattly enoiigh when ecBE^azed 

 with the appearance presented by the branches, within tiie 

 lungs, of the bronchial passages of an ex or sheep, sndx 

 branches having leen cut longitudinally. The -word vsed 

 in the Greek text to denote the bi^nch^ is du^ifseis, 

 which indicates that they are iii ihe substance oi the hmgs. 



In a series of very important passages, AristDtle says tiiat 

 blood-vessels extend from the heart to the lung and inazidi 

 in the same way as the trachea, closely foUofwix^ its Hranrlifs 

 thronghont the whole lung. E^"~— :: the brandies d fee 

 blood-vessels and those of the : he says, there is no 



common duct, but byreas::" ::_,...■ : ' ""^e blood- 

 vessels receive air and tr;_:-^_ : hx one 

 of the blood-vessels leads to the left mi :^v ::_ifr to the 

 right chamber of the heart. Hf '-■ -■ - " ■ th? dis- 

 position of the blo>i- vessels az . - :: :l-f 

 bronchial tubes is such that no part ci : r --^ --^ 

 detected in which an air passage exists -,_,_: i sziill 

 blood-vessel.! 



These passages are interesting because they foreshadow 

 a conception of that interchange c^ gases, between the 

 blood and the air within the hmgs, which is an important 

 effect of the process of respiration. Aristotle believed thas 

 air passed, in some way, from the sm all air ptassages into 

 the closely adjacent branches of the pulmonary blo>d-vessels. " 

 and that these branches transmitted it to the heart. He 



* H. A. i. e. IS, 5. 7. t liii, L c, ISL s. 7. 



I Ihid^ i. c. 14. s. S, iii. e. S. ?. 4. 



