MALE GENITAL OBGANS. 853 



which it is unitecl by a plentiful cellular tissue ; externally, it responds to 

 the posterior wall of the inguinal canal and the dartos. 



It is the contraction of the cremaster that causes the sudden ascent of 

 the testicle. 



DAKTOS. The tissue composing this tunic is contractile; it is con- 

 stituted by a mixture of elastic and unstriped muscular fibres. The dartoic 

 tunic does not reach the inguinal canal ; consequently, it does not cover 

 that part of the tunica vaginalis. It forms a pouch below the inguinal ring, 

 and is spread from around the margin of this on to the neighouring parts, to 

 which it adheres somewhat closely ; it is prolonged, gradually thinning, into 

 the sheath of, and even on to the penis itself, and to the tunica abdominalis, 

 as well as between the thighs. The two pouches it forms are quite in- 

 dependent of each other, never becoming confounded, though placed in 

 contact on the mesial line to form a double partition (septum scroti), whose 

 leaves are separated above for the passage of the penis. The dartos is in 

 relation, inwardly, with the fibrous and erythroid tunics, from which it is 

 isolated by an abundance of lamellar cellular tissue, which is very condensed 

 towards the globus major epididymis, and forms at this point a kind of cord 

 that passes from the fibrous tunic to the dartos, adhering strongly to each. 

 Externally, the dartos is covered by the scrotum. 



This tunic determines the vermicular movements of which the scrotum 

 is the seat. 



SCROTUM. The different membranes enumerated above are double, one 

 being for each tunica vaginalis ; but the scrotum constitutes a single pouch, 

 enveloping the two testicles at the same time. It is merely the portion of 

 skin covering this region, and is thin, and so closely adherent to the dartos, 

 that it can only with difficulty be separated from it. It is covered by 

 very short fine hair, and the extremely numerous sebaceous follicles in its 

 texture secrete an unctuous matter that renders its surface soft to the 

 touch. 



(There are also numerous sudoriparous glands, and these, with the 

 sebaceous glands, keep the skin soft and pliable, and modify the effects of 

 friction during progression. On its surface it shows a raphe or seam in the 

 middle, which is a trace of its primary division, and corresponds to the 

 median septum separating the testicles.) 



2. The Testicles. (Figs. 397, 398, 401.) 



External Conformation. Each testicle is oval in shape, flattened on both 

 sides, lodged in the cul-de-sac of the tunica vaginalis, 1 and suspended at the 

 extremity of the spermatic cord. The description of this organ is extremely 

 simple ; it offers for study two faces, two borders, and two extremities. 



The faces, external and internal are smooth and round. The inferior 

 border is convex and free, like the faces ; the superior, almost straight, is 

 related to the epididymis, which adheres to it by its head and tail. 



Means of Attachment. The testicle is freely pendent in the lower 

 part of the tunica vaginalis, where it cannot readily be displaced, because of 

 the narrowness of the space containing it. It is suspended, by its upper 



1 One or both testicles may be retained in the constricted portion of the tunica 

 vaginalis, or remain in the abdomen ; animals in which this occurs are named monorchids 

 or cryptorchids. The absence of one or two testicles (anorcMdism) is extremely rare. 

 Ectopise of the testicles is the designation applied to these organs when they are found 

 elsewhere than in their ordinary situation. 

 57 



