52 MECHANISM OF BREATHING. 



small oblique, and the transverse) aid in respiration. Consequently, 

 when they are well developed, the flank is not so hollow as it would 

 be if they were wanting in size. 



No hard and last line can be drawn between tranquil and forced 

 breathing ; although the broad differences between them are clearly 

 marked. 



In order that the horse may have his breathing power fully de- 

 veloped, it is necessary that the capacity of the chest at the end of 

 an act of expiration, should differ as much as possible from what it 

 will be at the termination of the act of inspiration. For this reason 

 the chest should be deep, the ribs well arched, and, at the same 

 time, they should have a good inclination to the rear. The back 

 ribs should be long, so as to augment the size of the chest ; and the 

 muscles which move the ribs, as well as the muscles of the belly, 

 should be largely developed. Further allusion will be made, in Chapter 

 XVII., to the shape of the chest and ribs. 



