THE TESTICLES. 785 



necessary to do little more than describe the mechanism of erection and of 

 the ejaculation of semen. 



The Testicles. The testicles are two symmetrical organs, situated, during 

 a certain period of intraiiterine life, in the abdominal cavity, but finally de- 

 scending into the scrotum. Immediately beneath the skin of the scrotum, is 

 a loose, reddish, contractile tissue, called the dartos, which forms two distinct 

 sacs, one enveloping each testicle, the inner portion of these sacs fusing in 

 the median line, to form a septum. Within these two sacs the coverings of 

 each testicle are distinct. These organs are suspended in the scrotum, by the 

 spermatic cords, the left usually hanging a little lower than the right. The 

 coverings for each testicle, in addition to those just mentioned, are the inter- 

 columnar fascia, the cremaster muscle, the infuudibuliform fascia, the tunica 

 vaginalis and the proper, fibrous coat. 



The tunica vaginalis is a shut sac of serous membrane, covering the tes- 

 ticle and epididymis and reflected from the posterior border of the testicle to 

 the wall of the scrotum, lining the cavity occupied by the testicle on either 

 side and also extending over the spermatic cord. This tunic is really a 

 process of peritoneum, which has become shut off from the general lining of 

 the abdominal cavity. The spermatic cord is composed of the vas deferens, 

 blood-vessels, lymphatics and nerves, with the coverings already described 

 which expand and surround the testicle. 



Beneath the tunica vaginalis are the testicles, with their proper, fibrous 

 coat. These organs are ovoid, and flattened laterally and* posteriorly. " They 

 are an inch and a half to two inches (38*1 to 5O8 mm.) long, about an inch 

 and a quarter (31-8 mm.) from the anterior to the posterior border, and 

 nearly an inch (25 '4 mm.) from side to side. The weight of each varies from 

 three-quarters of an ounce to an ounce (21*2 to 28 - 3 grammes), and the left 

 is often a little the larger of the two " (Quain). The proper, fibrous coat 

 is everywhere covered by the closely adherent tunica vaginalis, except at the 

 posterior border, where the vessels enter and the duct passes out. At the 

 outer edge of this border, is the epididymis, formed of convoluted tubes, pre- 

 senting a superior enlargement, called the globus major, a long mass running 

 the length of the testicle, called the body, and a smaller, inferior enlarge- 

 ment, called the globus minor. This too is covered with the tunica vaginalis. 

 Between the membrane covering the testicle and epididymis and the layer 

 lining the scrotal cavity, is a small quantity of serum, just enough to moisten 

 the serous surfaces. At the superior portion of the testicle are one or more 

 small, ovoid bodies, called the hydatids of Morgagni, each attached to the 

 testicle, by short, constricted processes. These have no physiological im- 

 portance and are supposed to be the remains of foetal structures. 



The proper, fibrous coat of the testicle is called the tunica albuginea. It 

 is white, dense, inelastic, measures about -% of an inch (1 mm.) in thickness, 

 and is simply for the protection of the contained structures. Sections of the 

 testicle, made in various directions, show an incomplete, vertical process of 

 the tunica albuginea, called the corpus Highmorianum or the mediastinum 

 testis. This is wedge-shaped, about of an inch (4-2 mm.) wide at its su- 



