[14] “Lectures on the Physiology of the Circulation in Plants, in the Lower Animals, and in Man.”—Edinburgh Medical Journal for January and February 1873.
[15] Muscles virtually possess a pulling and pushing power; the pushing power being feeble and obscured by the flaccidity of the muscular mass. In order to push effectually, the pushing substance must be more or less rigid.
[16] The extensor muscles preponderate in mass and weight over the flexors, but this is readily accounted for by the fact, that the extensors, when limbs are to be straightened, always work at a mechanical disadvantage. This is owing to the shape of the bones, the conformation of the joints, and the position occupied by the extensors.
[17] “On the Arrangement of the Muscular Fibres in the Ventricles of the Vertebrate Heart, with Physiological Remarks,” by the Author.—Philosophical Transactions, 1864.
“On the Muscular Arrangements of the Bladder and Prostate, and the manner in which the Ureters and Urethra are closed,” by the Author.—Philosophical Transactions, 1867.
“On the Muscular Tunics in the Stomach of Man and other Mammalia,” by the Author.—Proceedings Royal Society of London, 1867.
[18] Lectures “On the Physiology of the Circulation in Plants, in the Lower Animals, and in Man,” by the Author.—Edinburgh Medical Journal for September 1872.
[19] That the movements of the extremities primarily emanate from the spine is rendered probable by the remarkable powers possessed by serpents. “It is true,” writes Professor Owen (op. cit. p. 261), “that the serpent has no limbs, yet it can outclimb the monkey, outswim the fish, outleap the jerboa, and, suddenly loosing the close coils of its crouching spiral, it can spring into the air and seize the bird upon the wing.” . . . “The serpent has neither hands nor talons, yet it can outwrestle the athlete, and crush the tiger in the embrace of its ponderous overlapping folds.” The peculiar endowments, which accompany the possession of extremities, it appears to me, present themselves in an undeveloped or latent form in the trunk of the reptile.
[20] The Vampire Bat of the Island of Bonin, according to Dr. Buckland, can also swim; and this authority was of opinion that the Pterodactyle enjoyed similar advantages.—Eng. Cycl. vol. iv. p. 495.
[21] Comp. Anat. and Phys. of Vertebrates, by Professor Owen, vol. i. pp. 262, 263. Lond. 1866.