. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. MONOTREMATA. 405 Fig. 201. 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 lact
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. MONOTREMATA. 405 Fig. 201. 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 th
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