THE TESTES. 651 



the peritoneum, during the descent of the testes from the ab- 

 domen into the scrotum. After the descent of the testes into 

 the scrotum, the canal for its passage hecomes closed, and 

 this, like all serous membranes, presents the form of a shut 

 sac. One portion of it lines the inner surface of the dartos, 

 and is called the parietal ; the other is reflected upon the 

 forepart and sides of the testicle, and is the visceral or 

 tunica vaginalis testis. Between the two portions is the 

 smooth surface and cavity in which the secretion occurs. 

 This membrane is loosely attached to the scrotum and epi- 

 didymis, but firmly to the testis, or rather to the next 

 membrane, the tunica albuginea. 



The tunica albuginea forms the proper coat of the testis, 

 is in direct contact with the gland, consists of a dense 

 fibrous structure, of a bluish white color, and serves to 

 preserve the organ in its proper shape. From its union 

 with the tunica vaginalis, it is called a fibro-serous mem- 

 brane, such as the pericardium and dura mater. After 

 investing the testis, it is inflected at the posterior part, 

 into the interior of the gland, by a vertical partition con- 

 eisting of two laminse, called the mediastinum testis, or 

 corpus Higlimorianum, between which are found the vessels, 

 nerves, and ducts. Fibrous cords radiate, in great num- 

 bers, from this mediastinum to the inner surface of the 

 tunic, and are called trabeculce septulce. 



The tunica vasculosa, so named by Sir Astley Cooper, 

 lines the interior of the albuginea, and is regarded as the 

 nutrient membrane of the testis, bearing the same relation 

 to the latter, that the pia-mater does to the brain. It is a 

 very delicate membrane, consisting of a cellular web, con- 

 taining the minute ramifications of the spermatic vessels, 

 dipping into the substance of the gland, and sending pro- 

 cesses between the several lobules. 



On dividing the tunica albuginea, the proper substance 

 of the gland is seen presenting a soft, grayish, or yellowish 

 appearance, consisting of numerous delicate threads, loosely 

 connected together, and which may be drawn out, for two 

 or more feet, without breaking. These are the tubuli semini- 



