INTERNAL ORGANS OF GENERATION. 



39 



inguinal ring, and anteriorly it presents a little enlarged appendix. Be- 

 tween the two layers composing this band, is a thin muscle similar to the 

 cremaster of the male before the descent of the testicle into the scrotum ; 

 this band is the analogue of the round ligament in woman. The uterus 

 is also maintained in its position by the vagina posteriorly, and by the 

 peritoneum which at this part forms four bands — the redo-iiterine and 

 vesico-uterine. 



The interior of the uterus is divided into three compartments, corre- 

 sponding to its divisions into body and cornua. The cavity of the body 

 communicates with the vagina by a narrow canal which traverses the aon- 

 striction or cervix of the uterus, and is designated the caiial of the cervix. 

 In all the domesticated animals, except the Rabbit, this canal is pro- 

 longed into the anterior extremity of the vaginal cavity like the end of a 

 tap into a barrel j forming a very marked protrusion — the cervix. In 

 this is the opening {orificium uteri externum) leading from the vagina to 

 the body of the uterus — the os uteri or os tincce ; around this aperture 

 the utero-vaginal lining membrane is curiously arranged in transverse 

 rugae disposed in a circular manner, and which gives to this prominent 

 part the appearance of a radiating flower. In woman the rugae of the 

 canal are differently disposed, and resemble the branches from the stem 

 of a tree ; consequently, they have been named the arbor vita uterina. 



The uterus is composed of three membranes — an external^ or serous ; 

 a middle, or muscular ; and an internal, or mucous tunic. The serous or 

 peritoneal membrane envelops all the organ, and is in reality only an ex- 

 pansion of the broad ligainents which are prolonged backwards on the 

 posterior extremity of the vagina, which they encircle and then pass to 

 ' the rectum and bladder, as well as to the lateral parietes of the pelvis, 

 constituting the four ligaments already referred to. Between the two 

 cornua this membrane forms a peculiar frasnum, which is very developed 

 in solipeds. Owing to this arrangement, the cervix does not receive any 

 peritoneal covering. The muscular layer is composed of longitudinal and 

 circular fibres, analogous to those of the small intestines. At the insertions 

 of the broad ligaments into the uterus, a series of fasciculi are given off 

 from this layer, which pass up between the folds composing them, and 

 have been found throughout their extent, especially towards the ovaries. 

 The fibres composing this coat belong to the class of non-striated or in- 

 voluntary muscles, being made up of fusiform nucleated fibres lodged in 

 a matrix of exceedingly coherent granular matter. The appearance of 

 this coat is different to that of ordinary muscle,- being much more dense 

 and of a faint yellowish-red hue, like the middle coat of arteries or the 

 small intestines. The superficial set of fibres are irregularly longitudinal 

 in their direction, and frequently interlace with each other ; the deep set 

 is circular, especially around the orifice of each oviduct and the os uteri, 

 where they are thick and close ; though even among these fibres irregu- 

 lar fasciculi pass in different directions. Both layers are thicker in the 

 cornua than the body ; their obvious function is to diminish the volume 

 of the uterus during parturition. 



At an early period of life these fibres are perceptible, but during gesta- 

 tion they are greatly increased, and present a manifest striation. Their 

 increase is doubtless to permit the necessary dilatation of the uterus, with- 

 out allowing its parietes to become too attenuated and feeble ; though to 

 some extent they do diminish in thickness, according to the species. The 

 inner set are but loosely adherent to the lining or mucous membrane of the 



