2j6 be ffymas. [Book IX. 



through the whole fubftance of each lung, fo that by 

 inflating one lobule the air paffes into the reft. The 

 ufes of the lungs are of the moft important nature, 

 and will be confidered in a feparate chapter on the 

 fubjecl: of refpiration. 



The thymus, the fituation of which has been juft 

 mentioned, is foft, andofafpongy texture. It is very 

 large in the foetus, and is filled with a white thin li- 

 quor ; in adults it is hard, fmall, and gradually decays. 

 It is not difcovered to have any excretory duft, and 

 its yfe is unknown. 



