THE GENITAL ORGANS OF THE MALE. 



975 



6. The Penis. 



The penis is the male organ of copulation, and results from the union of the 

 corpus cavernosum and the spongy portion of the urethra. These parts have 

 already been described ; so it now remains to consider the organ in its entirety. 



The penis commences at the ischial arch, passes between the thighs and the 

 two dartoid sacs containing the testicles, and is prolonged beneath the belly, 

 where it terminates in a free extremity. 



All the portion comprised between the ischial arch and the scrotum is 

 maintained and deeply covered by the sm'rounding textures, and is named the 

 fixed portion of the penis. The remainder of the organ — its anterior moiety — 

 is, on the contrary, its free p)ortion, as it forms a detached appendage sustained 

 by a cutaneous fold — the sheath (or prepuce). 



The Fixed Portion occupies the perinasal region and that between the 

 thighs, where it is enveloped by 



the arteries, veins, and nerves ^'g- ^24. 



already known, as well as by a 

 large quantity of connective tissue 

 (and the skin). 



The Free Portion is lodged 

 in the prepuce during the inactive 

 condition of the organ, but pro- 

 trudes from it when in a state of 

 erection. It is then seen to be 

 covered by a smooth, unctuous, 

 tegumentary membrane with 

 numerous papillae, and of variable 

 colour, though most frequently it 

 is black or variegated. Its base 

 presents a slight circular enlarge- 

 ment, due to the accumulation, 

 beneath the mucous membrane, of 

 a small annular mass of elastic 

 and contractile tissue. Its ex- 

 tremify or glans is also a circular enlargement, lunited behind by a salient ridge 

 — the corona glandis — which is notched inferiorly, and at the moment of ejacu- 

 lation assumes a considerable development, its shape being then not unlike 

 the rose of a watering-can. This enlargement has for its basis the terminal 

 expansion of the urethral erectile tissue, and presents on its anterior face : 1. In 

 the centre, a rounded prominence due to the anterior point of the corpus cavern- 

 osum. 2. Beneath this, the urethral tube encircled by a fossa. 3. At the 

 bottom of the fossa, and below the urethra, the orifice of a double cavity —the 

 urethral sinus, which widens at the bottom, and in which accumulates sebaceous 

 matter that sometimes becomes so hard as to prevent the flow of the urine, by 

 compressing the tube. 4. Inferiorly, the suburethral notch. 



The dermis covering the extremity of the penis is rich in nerves which, 

 according to Kraiise, have round dilatations which he designates as " terminal 

 genital corpuscles." 



To complete the description of the penis, there only remain to be described : 

 1. Two suspensory and retractile ligaments which concur, with the natural elasti- 



LONGITUDINAL SECTION OF THE FREE EXTREMITY OF 

 THE horse's penis IN A RELAXED STATE. 



1, Erectile tissue of the corpus cavernosum ; 2, urethra; 

 3, fossa navicularis ; 4, urethral tube ; 5, erectile 

 tissue of the urethra; 6, ditto of the glans; 7, 

 corona glandis ; 8, urethral sinus. 



