DIAPHRAGM IN THE OX. 93 



the ox, as is commonly the case in animals without clavicles, 

 is more compressed on the sides than the chest in man that 

 is to say, the chest is deeper proportionately from sternum to 

 spine than in man. In the ox there are six lumbar vertebrae, 

 or one more than in man the same as in the horse and 

 sheep. The sacral and caudal vertebrae in the ox are the same 

 as in the sheep namely, four of the former and sixteen of the 

 latter ; in the horse there are but two sacral, while there are 

 seventeen caudal vertebrae. Of the pelvic bones the iliac 

 bones are developed to a great breadth in the ox. 



The midriff or diaphragm, a highly muscular partition, and 

 a principal agent in respiration, divides the chest from the 

 abdominal cavity. The diaphragm is also an important agent 

 in the evacuation of the bowels and bladder ; for, though the 

 diaphragm and abdominal muscles commonly act in antag- 

 onism to each other that is to say, in ordinary cases, the 

 contraction of the muscular fibres of the diaphragm causes 

 the abdominal organs to move backwards, and the abdominal 

 muscular parietes to protrude, while, in turn, the contraction 

 of the muscular fibres of the abdominal parietes pushes back 

 the diaphragm, and so diminishes the cavity of the chest yet, 

 when the diaphragm and the abdominal muscular parietes act 

 simultaneously, the whole contents of the abdominal cavity, 

 and also the contents of the pelvis, are powerfully compressed. 

 Hence this is the state of the parts, not merely in the evacu- 

 ation of the bowels and bladder, but in violent vomiting and 

 in the expulsion of the birth. To which may be added every 

 great effort of the whole frame ; for here the aperture of the 

 larynx being closed, so that air cannot escape as in expiration, 

 the whole chest, abdomen, and pelvis are strongly compressed 

 at once, the effect of which is, that the entire frame becomes 

 one solid unyielding pillar for the muscles of the extremities 

 and neck to pull upon. 



