:32 OBSTETRICAL ANATOMY, 



and adipose tissue, and fascia, with various muscles, bloodvessels, and 

 nerves. 



The internal limits of the vulva are defined by the constriction or 

 ■bulb, which forms a marked prominence in early life, but tends to dis- 

 .appear in relaxed folds after the animal has brought forth young several 

 times. The dimensions of this aperture are rather adapted for the 

 passage of the foetus than the penis ; though its narrowness is some- 

 times an obstacle to delivery in a primipara. The limbs, body, or head 

 of the foetus are at times arrested at the superior or perineal com- 

 missure, which they so distend as to threaten laceration of that part. 

 In emaciated animals, and particularly Mares, the vulva is deeply 

 retracted above the ischia, and consequently disposes them to be injured 

 in this region during coitus, by the accidental introduction of the male 

 organ into the anus — the mechanical action of which damages, and may 

 even rupture, the rectum. Eainard alludes to several occurrences of 

 this kind, which terminated in the death of the Mares. 



SECTION 11.— THE MAMM^. 



The mamvice, or udders, may be said to be appendices to the external 

 organs of generation. They are the glands destined to secrete the fluid 

 — milk — which is to nourish the young animal for some time after birth. 

 In early life they are rudimentary, but become developed with age, and 

 attain their full dimensions when the female is capable of reproduction ; 

 and especially at the full period of gestation, when their function is 

 about to be carried on actively. After parturition their largest develop- 

 iment is reached, and when the young creature has completed its term 

 ■of sucking, they lose their activity and diminish considerably in size. 

 In the Mare they are two in number, placed beside each other in the 

 inguinal region, about nine inches in front of the vulva, where they 

 take the place of the scrotum in the male. Externally, they appear as 

 two hemispherical masses separated by a shallow furrow; each has in 

 its centre, on each side of the mesian line, a conical, slightly flattened 

 prolongation named the teat or niijple, which is perforated by several 

 orifices from which the milk escapes, and by which the young creature 

 obtains that fluid by suction. The two glands are retained in their 

 position by the fii:ie thin skin covering them, and which, destitute of 

 hair at the extremity of the teats, though elsewhere provided with a 

 soft short down, is smooth, pliable, and unctuous from the presence of 

 sebiparous follicles. At the base of the teat are a number of small 

 tubercles, which correspond to the areola of the nipple in woman ; these 

 ;are the glands. 



The mammge are also attached to the abdominal tunic by means of 

 several wide, short, but elastic bands, which bear some analogy to the 

 suspensory ligaments of the prepuce in the male. 



In STRUCTURE each udder oft'ers an envelope of yclloio elastic fibrous 

 tissue, glandular tissue, the simises or galactopUorous reservoirs, and the 

 lactiferous ducts, with excretory canals or onilk ducts. 



The elastic envelope, joined at the mesian line with that of the oppo- 

 site udder, is strengthened by wide bands detached from the tunica 

 abdominalis ; it furnishes from its internal face numerous prolongations 

 which, crossing each other in the mass of the gland, form septa or parti- 

 tions that divide it into distinct lobes and lobules, which are in this way 



