. Cassell's natural history. Animals; Animal behavior. raouth by the nostrils which are supplied with valves. When in the mouth, which is closed on all sides, with the exception of the throat, where are the gill or branchial slits, the water, acted upon by the muscles which cover them, traverses their spaces, and bathes the branchiae, before its exit through the slits. The eyes are perfectly formed at this time, and the mouth has changed its position from below to the extremity of the head. It is very small, and there are no teeth, but minute horny plates are on the jaws, sufficiently strong t
. Cassell's natural history. Animals; Animal behavior. raouth by the nostrils which are supplied with valves. When in the mouth, which is closed on all sides, with the exception of the throat, where are the gill or branchial slits, the water, acted upon by the muscles which cover them, traverses their spaces, and bathes the branchiae, before its exit through the slits. The eyes are perfectly formed at this time, and the mouth has changed its position from below to the extremity of the head. It is very small, and there are no teeth, but minute horny plates are on the jaws, sufficiently strong to tear the soft animal and vegetable sub- stances which form the food. The Tadpole has a digestive system, the stomach being succeeded by an intestine which is of nearly equal size throughout its length, which is great. It is at least ten times as long as the inside of the body, and is curled up in a coil, and it occupies most of the abdominal cavity. During the growth of the Tadpole, and its change into the perfect Frog or Toad, it becomes shorter in pro- portion to the length of the animal, until at last it is not one-quarter of its original length. The tail soon becomes de- veloped sufficiently to move, and to move its possessor, and the colour of tha body changes, be- coming a soft olive-green instead of black, the abdomen being dotted with golden-yellow. The external form thus altered re- mains for some time, and the rudiments of the hind limbs appear, the toes budding at their extremities. Soon the fore limbs do the same. Then, as the hinder limbs increase, the tail is removed by absorption, which begins at the tip. When the branchisB have ceased their function, and lungs have developed, the creature is tail-less, and having long hind legs, comes to land, for it has become cajiable of respiring air with its lungs, and of hopping and jumping to search after small insects and worms. As growth proceeds, the webs to the digits, barely visible at first, become important struct
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Keywords: ., bookcentury1800, bookdecade1890, booksubjecta, booksubjectanimals
