MAMMARY GLA N D S .—Syn . Les glandes nainimaires, Fr., Die Mitch, die Brust-driisen, Germ. These important organs of secretion are the peculiar characteristic of the highest division of the animal kingdom, 31ammalia. In a physiological point of view they should be regarded as uterine appendages, as a por tion of that series of instruments which Na ture has provided in greater or less number, according to the ultimate perfection of the animal, for its gradual development. Their close proximity to the ovarian apparatus in some Mammalia, the cetacea for instance, and their peculiar structure and function in the Marsupiata, confirm this view of their phy siological character. It is interesting to trace how gradually they have been removed from their caudal position to the atlautal portion of the body, so that in the human species, where the instincts are subjugated to the control of reason, and the helplessness of the infant has been made the means of moral training to the mother, these organs are brought towards the anterior, the nobler portion of the body.
It must not, however, be supposed that this change of position is sudden, any more than any other step in the scale of progressive deve lopment of organized beings. Formerly it was supposed that the re-connection of the ovum to the mother through the medium of blood vessels collected into a placenta was as universal throughout the class Mammalia as the presence of these glands ; but the careful researches of Professor Owen have proved that the Marsu piata and most probably some of the Mono tremata form an exception to this rule. The fact is interesting in reference to the present subject from the greater importance which is given to the mamma in consequence of the ab sence of this vascular connection, and the addi tion of accessory structures which are absent in the more perfect mammalia.
The arrangement of the secreting membrane of mammary glands has been universally found to be vesiculated, the only difference in differ ent classes of animals consisting in the extent of secreting surface, owing to differences in the size of the cells, and their greater or less concen tration within a circumscribed space. This
vesiculated structure was described in 1751 by Duvernoi* in the hedgehog (Trans. of the Petersburg Academy), and in the human spe cies it was discovered by Cruikshank, -and de scribed in his work on the absorbent glands, the second edition of which was published in 1790. At page 209 his words are, " The acini are small vesicles like Florence flasks in miniature ; in these, the arteries secreting the milk termi nate; and from these the excretory ducts, or the tubes carrying off the milk take their origin. The existence of such vesicles has been doubted ; Dr. Hunter doubted till my injections con vinced him of the fact." He then goes pn to explain of injecting, and concludes by saying that preparations exhibiting this fact may be seen in the anatomical collection in Great Windmill-street, which he had made fifteen years previously.
Midler, to whom the above fact was known, states that Mascagni recognised and demon strated the vesicular ends of the lactiferous tubes and the absence of all direct commu nication with the bloodvessels, in his Pro dromo della Grande Anatomia, Firenze, 1819.
Ile refers also observations of Bunn on the vesicles of the mamma of the horse, ox, and goat; to those of Von Baer on the vesicles in the mamma of the Delphinus Pho ccena, to those of Van Hoeven and Vrolik in the same, and in the Balxna rostrata, and of Itleckel in the Ornithorhynchus, adding ori ginal observations and illustrations of his own, which demonstrate the same vesiculated struc ture in the hedgehog and rabbit.
During the course of the present year, 1840, the anatomy of the human breast has been des cribed in a manner by Sir A. Cooper that leaves us nothing to desire, and the minuteness and accuracy of his descriptions are only equalled by the beauty and fidelity of the plates which represent the interesting results of his labours. In our description, therefore, of the human breast we shall do little more than draw from this deep well of instruction.