" They are very numerous and large for the size of the part, and rather spongy at their extremities.
" They are very vascular bodies, and I have given a figure of them injected. The minute arteries which pass from the base towards the apex of the nipple send numerous branches to the papilla cutis, which divide into little bushes of vessels in each papilla and terminate in veins.
"The veins also are very numerous, and they will be seen injected, forming bushes similar to the extremities of the arteries.
" The application of the child's lips, the draw ing of the nipple in the motions of the child's head, and the suction produced by its mouth, produce so much excitement as to occasion erection of the nipple." The nipple is carefully connected with the gland by means of a firm fascia encircling the lactiferous tubes derived from the general fibrous tissue of the breast and thorax.
The areola.—This term has been applied to the coloured circle which surrounds the nipple. It is smooth until the period of puberty, when it becomes slightly tuberculated. Its diameter in a child is about half an inch ; at puberty and in young women double that size, and during lactation is as much as two inches or more, not again changing except in very old age, when it almost disappears.
The change of the colour of the areola from a reddish tint to a dark brown as the result of impregnation is well known to the practitioner. The cuticle is thin as in the nipple. Speaking of the cntis of the areola Sir A. Cooper observes, that " when the areola is examined with attention after the separation of the cuticle and rete mucosum, its surface is fgand to be covered with papillm like those oche nipple, but of smaller size, although stiil extremely distinct. They are smallest at the circumference of the areola, but gradually increase in size as they approach the nipple. They are disposed in circles, their bases fixed in the cutis, and the apex of each is directed towards the nipple, so that they are opposed to the papilla of the lips of the child. They are very vascular and sensitive bodies". (See fig. 71.) The whole structure of the areola points to it as a continu ation of the nipple.
The nipple and areola are lubricated by the secretion of especial mucous follicles which surround them, called by Sir A. Cooper the
tubercles of the areola. " These glands are extremely vascular, lobulated, and cellular. Each orifice opens into an arborescent vessel or vessels." (See fig. 72).
We must next direct our attention to the internal structure of the breast, first as regards the protective arrangements.
the fascia enveloping the breast, like the tunica albuginea of the testicle, sends in pro cesses to support and protect the secreting membrane of the gland and suspend it in its situation. These processes are all denomi nated by Sir Astley the ligainenta suspensoria, (fig. 73). " The ends of these ligaments are spread out and incorporated with the posterior surface of the skin, and give it whiteness and firmness." The secerning portion of the gland con sists of the minute cells which were referred to at the commencement of this article, and we learn from Sir A. Cooper that " their size in full lactation is that of a hole pricked in paper by the point of a very fine pin ; so that the cellules, when distended with quicksilver or milk, are just visible to the naked eye. ( Fig. 74.) They are rather oval than round, being slightly elongated where the bunch of the lactiferous tubes springs from them ; but they appear more rounded to quicksilver, and when distended with milk than when filled with wax." These minute cells or cellules are bound up together so compactly as to form little bodies or " glandules," varying in size from a pin's head to that of a small tare. When separated from the rest of the gland but attached to the mammary duct, which originates in separate branches from its cellules, it presents a race mose appearance.
From the cellules the milk-tubes originate in a radiate form by small and numerous branches. They increase in size by repeated unions, and terminate by five or six branches in dilatations— the " reservoirs" of Sir Astley. " These recep tacles are of a conical form (see fig. 75) like the mammillary tubes, and they begin from the extremities of the larger branches of the milk-tubes and terminate in the straight ducts of the nipple." In most other classes of the Mammalia these reservoirs are much larger than in man, where they hardly deserve the title, and in the cow they are so capacious as to be capable of con taining at least a quart.