. Elements of comparative anatomy. Anatomy, Comparative. ^ TOT 41G COMPARATIVE ANATOMY. division undergoes differentiation; a number, generally not more than five, terminal joints can be distinguished as fingers and toes. As a part of the body which generally projects towards the exterior is more under modifying influences than any other part, we find a large number of adaptations in them; few parts of the body present so many metamorphoses as these terminal parts of the appendagesâ the hand and foot. The primitive union of the fingers or of the toes into a swim- ming-plate, represented by the
. Elements of comparative anatomy. Anatomy, Comparative. ^ TOT 41G COMPARATIVE ANATOMY. division undergoes differentiation; a number, generally not more than five, terminal joints can be distinguished as fingers and toes. As a part of the body which generally projects towards the exterior is more under modifying influences than any other part, we find a large number of adaptations in them; few parts of the body present so many metamorphoses as these terminal parts of the appendagesâ the hand and foot. The primitive union of the fingers or of the toes into a swim- ming-plate, represented by the hand and foot, is retained in the natatory membrane of many Reptiles, in the hind-limbs of many Birds, and also in a number of Mammals, where it is always con- nected with the adaptation of these appendages to the function of a swimming organ. "â The angulation of the limb at- tainedto,in connection with terres- trial locomotion, and which is also advantageous in aquatic locomo- g tion, becomes gradually different in the case of the two extremities; the difference corresponds to the functions performed by the an- terior and posterior extremities when moving about on land. These relations are distinctly seen even in the Amphibia (B) ; but the difference in position between the upper and forearm, and thigh and leg, is not well marked. The upper arm and thigh are turned outwards to almost the same extent. There is a greater difference between them in the Reptilia (G), and this is still more marked in the Mam- malia, where the planes in which Fig. 215. Diagram to show the differen. the angles of the limbs of cither tiation and alteration in the direction of ⢠j , n i , ,i the axes of the limbs in the Vertebrate. Sld°. aTe Set JP3 Parallel to tlie .A Fish, b Amphibian (the side-view, vertical median plane of the which one lias been obliged to give so as body. This gives greater inde- to compare it with the rest, gives to this pendence to tlie ]imbg wllich and to the ne
Size: 2311px × 1082px
Photo credit: © Paul Fearn / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, booksubjectanatomycomparative
