978 



GENERATIVE AFPABATUS. 



glands, enclosed in a mass of connective tissue and unstriped fibres ; they open into a commoa 

 central canal, which terminates in tlie vas deferens. 



Urethra. — This canal is inflected like the letter S. Its diameter regularly diminishes from 

 its commencement to its termination, wliich is not provided with a urethral tube, as iu 

 Solipeds. Internally it presents : 1. Immediately beyond the neck of the bladder, a short, but 

 very salient verumontanum, which divides into two mucous columns that gradually subside 



posteriorly. 2. Towards the ischial arch, a 

 valve the free border of which — directed down- 

 wards — covers a cul-de-sac from about three- 

 fourths to one inch deep. 



The structure of the urethra is also dif- 

 erent. The walls of the membranous portion 

 are tliicker than in the Horse ; they have a 

 layer of erectile tissue, and a sphincter muscle, 

 very thick below and laterally, the fibres of 

 which are inserted in the middle of the upper 

 surface, into an aponeurotic rapiie'. 



At the ischial arch, when the canal bends 

 downwards, the spongy tissue becomes more 

 abundant to form the hulh of the urethra ; but 

 the prominence at this point is chiefly due to 

 the accelerator urinas, as is shown in Fig. 

 526, C 4, This muscle is extremely powerful, 

 but it soon ceases beneath the ischial arch. 

 The trausversus perinasi is as strong as in 

 Solipeds. 



Glands annexed to the urethra. — Cowper's 

 glands are absent. Tlie prostate gland is not 

 voluminous, and forms, at the commencement 

 of the urethra, a little transverse yellow, bilo- 

 bate mass, beneath which pass the vasa 

 deferentia ; it also lies beneath the sphincter 

 muscle, and is prolonged for some distance on 

 the membranous portion of the urethra. 



PfMis. — In the Bull, the penis is long and 

 thin, and carried well forward beneath the 

 belly. It is enclosed at the perinseum in an 

 aponeurotic sheath, which is covered by the 

 iscbio-tibial muscles. This sheath is double, 

 its superficial layer being continuous with the 

 dartos, and it has the same physical cha- 

 racters; the deep layer is thin, white, and 

 inelastic. 



In front of the pubis, the penis describes 

 two successive curves — the S of the penis — the 

 first with its convexity forward;*, the second 

 backwards. It is at the second curve that 

 the suspensory ligmnents join tlie penis, and 

 continue along its sides to its extremity. 



The free portion of the organ — very taper- 

 ing — is covered by a fine, papillated, very 

 sensitive, rose-coloured mucous membrane. 



It is lodged in a narrow prepuce that ad- 

 vances much more forward beneath the ab- 

 domen than in Solipeds, and has at its opening a bunch of long stiff hairs. This cutaneous 

 sheath is moved by four subcutaneous muscles: two posterior or retractors (Fig. 527, 2) which 

 draw the sheath backwards, and concur in exposing the penis at the moments of its erection ; 

 and two anterior or protractor muscles (Fig. 527, 1) which carry the prepuce forward to its 

 former position. The latter are found in the Cow, and do not appear to be of any use. 



The two constituent portions of the copulatory organ are not joined in the same manner as 

 in Solipeds, the channel for the lodgment of the urethra being transformed into a complete 

 canal, by a narrow layer of the fibrous envelope of the corpus cavernosum. The latter is little 



J 1 



SECTIONS OF THE URETHRA OF THE OX AT 

 DIFFERENT POINTS. 



Af Intra-pelvic portion: 1, Urethral sphincter; 2, 

 erectile tissue ; 3, urethral canal ; 4, prostate 

 gland. B, The middle of the penis : 1, Fibrous 

 cord of the corpus cavernosum ; 2, urethral 

 canal ; 3, its erectile tissue ; 4, envelope of 

 the corpus cavernosum. C, At the crura of the 

 penis : 1, 1, Crura of the corpus cavernosum ; 

 2, urethral canal ; 3, its erectile tissue ; 4, 

 accelerator urinae ; 5, erector penis muscle. 



