640 HANDBOOK OF PHYSIOLOGY. 



the vagina is embraced by an orbicular muscle, the constrictor vngince 

 its external orifice, in the virgin, is partially closed by a fold or ring of 

 mucous membrane, termed the hymen. The external organs of genera- 

 tion consist of the clitoris, a small elongated body, situated above and 

 in the middle line, and constructed of two erectile masses or corpora 

 -cavernosa. They are not perforated by the urethra; of two folds of mu 

 cous membrane, termed labia internet or nyrnphaj and, in front of these, 

 of two other folds, the labia externa, or pudenda, formed of the external 

 integument, and lined internally by mucous membrane. Between the 

 nymphae and beneath the clitoris is an angular space, termed the vesti- 

 bule, at the centre of whose base is the orifice of the meatus urinarius. 

 Numerous mucous follicles are scattered beneath the mucous membrane 

 composing these parts of the external organs of generation; and at the 

 side of the lower part of the vagina are two larger lobulated glands; 

 Tulvo-vaginal or Duverney's glands, which are analogous to Cowper's 

 .glands in the male. 



B. The Genital Organs of the Male. 



The male organs of generation comprise the two Testes, in which 

 the semen is formed; each with its duct, the Vas Deferens, with the 

 accessory Vesicula Seminalis ; and the Penis, an erectile organ, 

 through which the semen as well as the urine is discharged. The Pros- 

 tate gland, the exact function of which is not understood, is generally 

 included in the same class. 



a The Testes. The secreting structure of the testicle and its duct 

 are disposed of in two contiguous parts, (1) the body of the testicle 

 proper, inclosed within a thick and tough white fibrous membrane, the 

 tunica albuginea, on the outer surface of which is the serous covering 

 formed by the tunica vaginalis, and (2) theepididymis and vas defer ens. 



The Vas deferens, or duct of the testicle, which is about two feet in 

 length, is constructed externally of connective tissue, and internally is 

 lined by a mucous membrane, covered with columnar epithelium; while 

 between these two coats is a middle coat, very firm and tough, made up 

 of unstriped muscle, chiefly arranged longitudinally, but also containing 

 some circular fibres. When followed back to its origin, the vas deferens 

 is found to pass to the lower part of the epididymis, with which it is 

 directly continuous (Fig. 429), and assumes there a much smaller diam- 

 eter with an exceedingly tortuous course. 



The Epididymis, which is lined, except at its lowest part, by colum- 

 nar ciliated epithelium (Fig. 429), is commonly described as consisting 

 (Fig. 429) of a globus minor (g}, the body (e), and the globus major (I). 

 When unravelled, it is found to be constructed of a single tube, measur- 

 ing about twenty feet in length. 



At the globus major this duct divides into ten or twelve small 



