. Essentials of biology presented in problems. Biology. 298 THE VERTEBRATE ANIMALS attached to the wings, aid in locomotion, while the wing itself, a modified arm, is one of the most evident adaptations to life in the air. Flight. — Watch a bird in flight. The tip of the wing usually describes a curve which results in the forming of the figure 8. The rate of movement of the wing differs greatly in different birds. The wing of a bird is slightly concave on the lower surface when outstretched. Thus on the downward stroke of the wing more resistance is offered to the air. Birds with long, thin wi
. Essentials of biology presented in problems. Biology. 298 THE VERTEBRATE ANIMALS attached to the wings, aid in locomotion, while the wing itself, a modified arm, is one of the most evident adaptations to life in the air. Flight. — Watch a bird in flight. The tip of the wing usually describes a curve which results in the forming of the figure 8. The rate of movement of the wing differs greatly in different birds. The wing of a bird is slightly concave on the lower surface when outstretched. Thus on the downward stroke of the wing more resistance is offered to the air. Birds with long, thin wings, as the hawks and gulls, move the wing in flight with much less rapidity than those with short, wide wings, as the grouse or quail. The latter birds start with much less apparent effort than the birds with longer wings; they are, however, less capable of sustained flight. Feathers. — Few people realize that the body of a bird is not completely covered with feathers. Featherless areas can be found on the body of any common bird, although tiny " pin feathers " are found on such areas as well as on other parts of the body. Soft down feathers cover the body, serving for bodily warmth. Larger feathers give the rounded contour to the body. In the wings we find quill feathers; these are adapted for service in flight by having a long hollow shaft, from which lateral interlocking branches are given off, the whole making a light structure offering considerable resistance to the air. Feathers are developed from the outer layer of the skin, and are formed in almost exactly the same manner as are the scales of a fish or a lizard. The first feathers developed on the body. Feathers of a meadow lark. '\\'hich of the above are used for flight ? How do you know ? From photograph loaned by the American Museum of Nat- ural Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearanc
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbiology, bookyear1911
