. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. BIRDS 295 yet flexible. They vary greatly in shape and also in number. The swan, seeking its food under water, has a neck containing twenty- three long vertebrae; the English sparrow, in a different environ- ment, has only fourteen short ones. Some bones, notably the breast- bone, are greatly developed in fly- ing birds for the attachment of the muscles used in flight. Bill. —The form of the bill shows adaptation to a wonderful Skeleton of a fowl; C, clavicle; C. V., cer- vical ver
. Elements of biology; a practical text-book correlating botany, zoology, and human physiology. Biology. BIRDS 295 yet flexible. They vary greatly in shape and also in number. The swan, seeking its food under water, has a neck containing twenty- three long vertebrae; the English sparrow, in a different environ- ment, has only fourteen short ones. Some bones, notably the breast- bone, are greatly developed in fly- ing birds for the attachment of the muscles used in flight. Bill. —The form of the bill shows adaptation to a wonderful Skeleton of a fowl; C, clavicle; C. V., cer- vical vertebrae; K., keeled sternum; , pelvic girdle; , pectoral girdle. Exercise for a Trip to a Museum or Zoological Park. — Note a number of different-shaped bills. How is the bill adapted to taking the food for the bird ? Seek for uses in each case. Remember that a bird uses its bill as some ani- mals use claws and teeth. Birds, ex- cept the parrot and some of the birds of prey, rarely use the claws in feeding. The bills vary greatly according to the habits of the birds. A duck has a flat bill for pushing through the mud and straining out the food; a bird of prey has a curved or hooked beak for tear- ing; the woodpecker has a sharp straight bill for piercing the bark of trees in search of the insect larvae which are hidden underneath. Birds never have teeth, except possibly in the embryo stage. The edge of the bill may be toothlike, as in some fish-eating ducks; these, however, are not true teeth. Frequently, too, the tongue has sharp tooth like edges which serve the same purpose as the recurved teeth of the frog or snako. With care you may be able to make out the use of the tongue in eating and drinking in some bird. Report in class the result of your observa- tions. Reason for High Temperature and Rapid Heart Beat in Birds. — ]Make observations on a bird as to the rapidity of the movements made in breath- ing (respiratory movements). Compare them with your own as to
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