ANIMAL CASTBATION. 83 



external, and when the perforation of the inguinal 

 space (Belgian method) is badly made, at the moment 

 the fingers are pressing against it, it tears easily in 

 its entire height. 



The entrance of the inguinal space is represented by 

 the inferior or external inguinal ring. Oval in form, 

 with its long diameter oblique backwards and in- 

 wards, it is essentially formed by two fasciculi of 

 fibres belonging to the great oblique muscle, which, 

 contiguous first, become isolated from each other and 

 form two curved edges surrounding the opening. 

 This entrance has two borders, lips or pillars, and 

 two angles or commissures. The antero-iuternal 

 border is deeply lined by the small oblique, whose 

 fibres reflect at this point, to become more horizontal. 

 The postero-external border is formed exclusively 

 by a portion of the aponeurosis of the great oblique, 

 continued immediately upwards by the crural arch 

 and downwards by the crural aponeurosis. 



The anterior or external commissure, more or less 

 resisting according to subjects, is formed by the 

 diverging fibres of the great oblique reinforced by a 

 few arciform fibres. The posterior or internal com- 

 missure corresponds to the tendon of the abdominal 

 muscles and the anterior border of the pubis. 



The bottom or summit of the iuguiual tract is 

 formed by the union of the two commissures. It is 

 bound by the line of insertion of the deep fibres of 

 the small oblique on the ilial portion of the crural 

 aponeurosis. The summit of the inguinal tract— 

 that is to say, the region where the peritoneum is to 



