. Animal locomotion or walking, swimming, and flying : with a dissertation on aëronautics. Fig. 49.—Foot of Grebe (Podiceps). In this foot each, toe is provided with itsswimming membrane ; the membrane being closed when the foot is flexed,and expanded when the foot is extended. Compare with foot of swau (), where the swimming membrane is continued from the one toe to theother.—(After Dallas.) consists of three swimming toes, each of which is providedwith a membranous expansion, which closes when the foot isbeing drawn towards the body during the back stroke, andopens out when it is being
. Animal locomotion or walking, swimming, and flying : with a dissertation on aëronautics. Fig. 49.—Foot of Grebe (Podiceps). In this foot each, toe is provided with itsswimming membrane ; the membrane being closed when the foot is flexed,and expanded when the foot is extended. Compare with foot of swau (), where the swimming membrane is continued from the one toe to theother.—(After Dallas.) consists of three swimming toes, each of which is providedwith a membranous expansion, which closes when the foot isbeing drawn towards the body during the back stroke, andopens out when it is being forced away from the body duringthe effective Fig. 50.—Diagram representing the double waved track described by the feetof swimming birds. Compare with figs. IS and 19, pp. 37 and 39, and withfig. 32, p. 68.—Original. In swimming birds, each foot describes one side of anellipse when it is extended and thrust from the body, theother side of the ellipse being described when the foot is flexedand drawn towards the body. The curve described by the rightfoot when pushed from the body is seen at the arrow r of ; that formed by the left foot when drawn towards thebody, at the arrow s of the same figure. The curves formed G 98 ANIMAL LOCOMOTION. by the feet during extension and flexion produce, when unitedin the act of swimming, waved lines, these constituting achart for the movements of the extremities of swimming birds. There is consequently an obvious analogy between theswimming of birds and the walking of man (compare fig. 50,p. 97, with fig. 19, p. 39); between the walking of man andthe walking of the quadruped (compare fi
Size: 3329px × 751px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubje, booksubjectphysiology
