122 ON RESPIRATION, 



winded horses, is a general thickening of their 

 substance', by whicli their elasticity is, in a 

 great measure, destroyed, and tlicir weight spe- 

 cifically increased, at the same time that their 

 capacity for receiving air is diminished. Dur- 

 ing life, the lungs entirely fill the cavity of the 

 chest, so as to leave no space between their out- 

 ward surface and the inward surface of the ribs ; 

 thus they dilate and contract, following up by 

 their own elasticity the action of the ribs and 

 diaphragm. Hence it is probable, that adhe- 

 sions of the lungs to the ribs are not so injurious 

 to respiration as might be imagined. 



If the chest is punctured in the dead sub- 

 ject, the external air rushes in, and the lungs 

 collapse ; but if the horse was broken-winded, 

 the lungs do not collapse, which proves that 

 they have lost their elasticity. This state of the 

 lungs sufficiendy accounts for the difficulty of 

 respiration, for, as their faculty of dilatation Is 

 in a great measure destroyed, the ribs cannot ex- 

 pand 



