172 ELEMENTS OF MAMMALIAN ANATOMY. 
efferentia. The epididymis is composed of a single greatly 
convoluted tubule of which the vas deferens is a continua- 
tion. The latter proceeds craniad to the external ab- 
dominal ring, which it enters to traverse the inguinal canal 
into the abdominal cavity. It then curves caudad and 
enters the urethra on its dorsal aspect in the region of the 
prostate gland. 
The inguinal canal begins with the external abdominal 
ring, which is an opening in the tendon of the external 
oblique muscle, and ends with the 
WV internal abdominal ring, which is an 
opening in the fascia of the trans- 
ie versalis muscle (Fig. 51). By acci- 
dent, a fold of the small intestine 
el in man sometimes descends through 
the inguinal canal, which condition 
t is known as hernia or rupture. 
Fic. 91. SPERMATOZOA ee A ; 3 
or Mate Germ CELLS. The penis is a cylindrical pointed 
A 400: . body about three centimeters long 
h, Head; t, tail. ‘ 3 
: when in repose. It is composed of 
two kinds of tissues arranged in three bundles. The corpus 
Spongiosum is the median ventral bundle, extending 
throughout the length of the organ, and at the end forms 
the glans or head. The two dorsal lateral bundles are the 
corpora cavernosa. They form the greater part of the penis 
proximad of the glans, and by diverging somewhat before 
their attachment on either side to the pubis and ischium 
form the crura. The penis is suspended from the wall of 
the abdomen by a fold of integument inserted at the base 
of the glans, and forming the prepuce. The latter is a 
free projection of skin covering the glans. In the midst 
of the penis is a small bone. The penis is the organ of 
copulation, and is composed of a spongy mass of elastic and 
muscular fibers richly supplied with highly distensible 
blood-vessels which when filled render the organ erect. 
