Chap. XXI] THE ORGANS OF GENERATION 459 



tatic portion of the urethra. Each has an external areolar, middle 

 muscular, and internal mucous coat. 



The scrotum. — The scrotum is a pouch which contains the 

 testes and a part of each spermatic cord. It consists of a layer 

 of skin, and the dartos. The skin is thick and dark, presents folds 

 or rugae, is furnished with sebaceous glands, and covered with short 

 hairs. The dartos is a thin tunic of a reddish color consisting of 

 muscular fibres and elastic tissue and containing numerous blood- 

 vessels. It is continuous with the superficial fascia of the groin 

 and perineum. It sends in a partition, which separates the two 

 testes. 



The spermatic cord, — The spermatic cord forms the pedicle 

 of each testis and extends from the internal abdominal ring to the 

 back of the testis. Each cord consists of the vas deferens, arteries, 

 veins, lymphatics, nerves, the layers of fascia which cover the 

 testis, and the remains of the peritoneal testicular process. These 

 parts are connected together by areolar tissue. 



The penis. — The penis consists of three more or less cylindrical 

 bodies of erectile ^ tissue enclosed in fibrous sheaths. The two 

 corpora cavernosa lie above and receive between them below 

 the corpus spongiosum, in which the urethra is contained. The 

 glans penis is continuous with the corpus spongiosum. The cov- 

 ering of the penis is of loose skin, but over the glans penis and 

 lining the prepuce it resembles mucous membrane. In this 

 region there is an abundant subcutaneous nerve plexus and 

 numerous Pacinian ^ corpuscles, so that it is possessed of acute 

 sensibility. 



The urethra. — The urethra extends from the bladder through 

 the corpus spongiosum to the end of the penis. It is usually di- 

 vided into three parts: (1) the prostatic urethra, (2) the mem- 

 branous urethra, and (3) the penile or spongy portion. The 

 length is usually given as eight inches (200 mm,), a large part of 

 which lies inside the pelvis. It is lined with mucous membrane 

 and furnished with numerous muscular fibres. 



' Erectile tissue is found in the clitoris, penis, and the nipples. The form, size, 

 and consistency of this tissue change according to the amount of blood contained 

 in it. An increased amount of arterial blood causes swelling, and consequent press- 

 ure on, and occlusion of, the veins. 



2 Pacinian corpuscles are specialized nerve-endings found in the genital organs 

 of both sexes, also in the palms of the hands, and the soles of the feet. (See Fig. 177.) 



