Chapter VIII.

1. Cartilage is of the same nature as bone, but it differs in the greater and less, and neither bone nor cartilage are reproduced if they are cut off. In sanguineous and viviparous animals living on the land the cartilage is imperforate, and does not contain marrow, like the bones; but the flat selachea, which have a cartilaginous spine, have a cartilage analogous to bone containing a liquid marrow. Viviparous animals, with feet, have cartilage about their ears, nostrils, and extremities of their bones.