. Biology and human life. Biology. THE HUMAN ORGANISM 275 Oall bladder Liver ^' Pancreas Jnlestine Kidney carving poultry or from studying the joints of meat and other that come from the butcher shop. 224. General plan of vertebrates. On page 16 we started to make a comparison between the human body, representing a vertebrate, and an insect body. The frog is a convenient ani- mal for showing the general plan of vertebrates. We note the main body, or trunk, with the head at one end and with two pairs of appendages. In the more familiar groups of vertebrates (mammals, birds, amphibian
. Biology and human life. Biology. THE HUMAN ORGANISM 275 Oall bladder Liver ^' Pancreas Jnlestine Kidney carving poultry or from studying the joints of meat and other that come from the butcher shop. 224. General plan of vertebrates. On page 16 we started to make a comparison between the human body, representing a vertebrate, and an insect body. The frog is a convenient ani- mal for showing the general plan of vertebrates. We note the main body, or trunk, with the head at one end and with two pairs of appendages. In the more familiar groups of vertebrates (mammals, birds, amphibians, and certain rep- tiles such as lizards and tur- tles) the posterior (hind) appendages are so much alike that we generally call them by the same name—legs. To be sure, the flippers of the seal or the whale resemble the fins of fishes more than they do the limbs of land animals, and the fins of fishes do not resemble our legs or arms at all, except perhaps in their positions on the body; yet they are truly homologous organs (see Figs. 122 and 123). The head is easily recognized in all classes, although it is not always on a distinct neck. The trunk of the frog consists of a body wall inclosing a large cavity. In the mammals, including man, the body cavity is divided into two chambers by a muscular partition called the diaphragm (see Figs. 84 and 124). Inside the cavity of the. Fig. 125. The viscera of the frog In the body cavity of the frog are lo- cated the principal breathing organs (the lungs); the principal digestive organs (stomach and intestines, liver and gall bladder, and pancreas); the principal excreting organs (the kidneys); the blood- pumping organ (the heart); and the re- productive organs (ovariesor testes). The largest blood vessels, air tubes, and con- necting ducts are also in this cavity. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustratio
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Keywords: ., bookcentury1900, bookdecade1920, bookpublishe, booksubjectbiology
