File:The cyclopædia of anatomy and physiology (1847) (20200934193).jpg

Title: The cyclopædia of anatomy and physiology
Identifier: cyclopdiaofana03todd (find matches)
Year: 1847 (1840s)
Authors: Todd, Robert Bentley, 1809-1860
Subjects: Anatomy; Physiology; Zoology
Publisher: London, Sherwood, Gilbert, and Piper
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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MONOTREMATA. 405 Fig. 201
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Terminal ducts, and lube of mammary gland, injected, twice natural sixe. strongly implying its fluid nature, and most contrary to the mode in which odorous sub- stances are excreted ; 3rd, the excretory ori- fices are by no means extended over so wide a space, in proportion, as in the Shrew, but col- lected into a point which we know to be not disproportionate to the size of the mouth of the young animal, and this point is situated in a part of the body convenient for the transmission of a lacteal secretion from the mother to her offspring. Compared with an ordinary mammary gland, that of the Ornithorhynchus differs chiefly in the absence of the nipple, and, consequently, of the surrounding vascular structure necessary for its erection. But the remarkable modifica- tion of the mouth in the young Ornithorhynchus removes much of the difficulty which previously attached itself to the idea of the possibility of an animal with a beak obtaining its nutriment by suction. The width of the mouth in the smallest observed Ornithorhynchus corres- ponds with the size of the mammary areola; and the broad tongue, extending to the apices of the broad, short, and soft jaws, with the fold of integument continued across the angle of the mouth, are all modifications which pre- pare us to admit such a co-adaptation of the mouth of the young to the mammary outlet of the parent, as, with the combined actions of suction in the recipient, and compression of the gland in the expellent, to effect this essen- tially Mammalian mode of nourishment. We may presume that a corresponding mo- dification of the mouth of the new-born animal obtains in the Echidna, since the mam- mary glands in this Monotreme* correspond in structure, and mode of termination of theexcre- tory ducts, with those of the Ornithorhynchus, As yet the secretion of the mammary glands of the Echidna has not been observed; but that of the Ornithorhynchus has been detected not only in the stomach of the young (ante p. 401), but oozing from the lacteal pores of the female, and by more than one competent observer.f Mr. George Bennett, describing his dissection of a female Ornithorhynchus shot at Mun- doona, New South Wales, on the 14th of November, the day before his arrival at that place, and which " had evidently just produced her young," and had very large mammary glands, thus records his obser- vation of their secretion. " The glands were very vascular on the surface, the mammary artery ramifying over them in a most beautiful and distinct manner. The fur still covered that portion of the integument on which the ducts terminated, and there was no appear- ance of a projecting nipple." " How different was the appearance in the recent state of this mammary gland from that which I had pre- viously seen at the Royal College of Sur- geons, in a specimen long preserved in spirits, in which I had the opportunity of witnessing the injection of the ducts with mercury by my friend Mr. Owen, the mercury exuding, as I have seen the milk from the similar ducts, upon the integuments."—Zoological Trans- actions, vol. i. p. 251. In a female Ornitho- rhynchus, which with her two full-furred young were captured alive by Mr. Bennett on the 28th of December, he says, " The milk that could be expressed from the glands was but trifling in quantity; and, in the mother of these young animals, such would have been expected to be the case, for they were capable of feeding upon more substantial diet."—Ibid. p. 254. Crural gland and spur.^—This remarkable * See Phil. Trans. 1832, p. 537, p!. xvii., figs. 2 and 3. f Hon. Lauderdale Maule, Proc. Zool. Society, part ii. p. 145. G. Bennett, Esq. ib. part i. p. 82. Partii. p. 141-11. Hf Meckel, loc. cit. p. 54, calls this peculiar sexual gland ' femoral,' observing," ne ipso no- mine de functione judicium proferam, forsan re- trahendam, hoc nomen a situ impono." As, how- ever, the femoral position is peculiar to the Orni- thorhynchus, the gland being popliteal in the Echid- na, I prefer a name derived from the word ' crus,' which has a more extended signification to the whole hinder extremity.

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