256 THE PHYSIOLOGY OF THE 



wards and backwards. One portion of the tendon, or 

 aponeurosis, by which it terminates, goes to the pubis, 

 while the stronger part proceeds to the inside of the 

 thigh. The separation here pointed out in mares shelters 

 the round ligament ; but in horses allows the passage of 

 part of the inguinal canal, and helps to form the outer 

 abdominal ring. The internal abdominal ring, and a por- 

 tion of the canal, intersects the transversalis abdominis, as 

 well as the internal oblique muscles. 



The foetal situation of the testicles is immediately behind 

 the kidneys, whence they eventually make their way 

 into the scrotum. When situated within the cavity of the 

 abdomen they are enveloped by peritoneum, and are each 

 of them attached to a ligamentous substance of a pyramidal 

 shape ; whose base adheres to the testicle, while its apex is 

 continued through the abdominal rings, to be fixed to the 

 bottom of the scrotum. This ligament, which is termed 

 gubernaculum testis, attains its full growth before birth ; 

 after which period, it begins to contract and shorten itself; 

 but, as it cannot draw the scrotum within the rings, nor free 

 itself from the testicle, it therefore draws downward the 

 gland, surrounded by its peritoneal covering. This progress 

 is carried on gi^adually ; but when the testicles have been 

 drawn to the abdominal ring, it is evident they must there 

 meet with some obstruction ; for the peritoneum, afterwards 

 brought down by the testicle at this period, lines the entrance 

 to the ring. The testicle having, by the contraction of the 

 ligament, been forced down the canal, lines it with peri- 

 toneum, and forms the internal coat to the scrotum. This 

 lining of peritoneum has nothing to do with that which 

 covers the testicles ; that remains upon the gland ; but the 

 extension of the peritoneum also brings with it a covering 

 for the cord. The gubernaculum having fulfilled its office 

 becomes absorbed. Nature, in her economy, refusing to 

 keep any thing which is of no service. By this means an 

 open communication is formed with the scrotal cavity, and 

 which remains free during life ; the horizontal situation of 

 the horse's body preventing frequent protrusion of the 

 abdominal contents through the ring. 



The gestatory term is generally considered to range be- 

 tween eleven and twelve months ; these periods forming the 



