. Animal locomotion or walking, swimming, and flying : with a dissertation on aëronautics. wimming;and in the movements of the wings of insects, bats, andbirds in flying. The straight and oblique muscles areusually found together, and co-operate in producing themovements in question; the amount of rotation in a partalways increasing as the oblique muscles preponderate. Thecombination of ball-and-socket and hinge-joints, with their con-comitant oblique and longitudinal muscular cycles (the formeroccurring in their most perfect forms where the extremitiesare united to the trunk, the latter in th
. Animal locomotion or walking, swimming, and flying : with a dissertation on aëronautics. wimming;and in the movements of the wings of insects, bats, andbirds in flying. The straight and oblique muscles areusually found together, and co-operate in producing themovements in question; the amount of rotation in a partalways increasing as the oblique muscles preponderate. Thecombination of ball-and-socket and hinge-joints, with their con-comitant oblique and longitudinal muscular cycles (the formeroccurring in their most perfect forms where the extremitiesare united to the trunk, the latter in the extremities them-selves), enable the animal to present, when necessary, an exten-sive resisting surface the one instant, and a greatly diminishedand a comparatively non-resisting one the next. This arrange-ment secures the subtlety and nicety of motion demanded bythe several media at different stages of progression. The travelling surfaces of Animals modified and adaptedto the medium on or in which they move.—In those landanimals which take to the water occasionally, the feet, as a. Fig. 10, Fig. 14. Fig. 10.—Extreme form of compressed foot, as seen in the deer, ox, etc.,adapted specially for land transit.—Original. Fig. 11.—Extreme form of expanded foot, as seen in the Oriiithorhyiichus,etc., adapted more particularly for swimming.— Original. Figs. 12 and 13.—Intermediate form of foot, as seen in the otter (tig. 12),frog (fig. 13), etc. Here the foot is equally serviceable in and out of thewater.—Origin 1. Fig. 14.—Foot of the seal, winch opens and closes in the act of natation,the organ being folded upon itself during the non-effective or return stroke,and expanded during the effective or forward stroke. Due advantage istaken of this arrangement by the seal when swimming, the animal rotatingon its long axis, so as to present the lower portion of the body and thefeet obliquely to the water during the return stroke, and the flat, or thegreatest available surf
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Keywords: ., bookcentury1800, bookdecade1870, booksubje, booksubjectphysiology
