. The anatomy of the frog. Frogs -- Anatomy; Amphibians -- Anatomy. THE SKIN AND THE SENSE-ORGANS. I. THE SKIN AND ITS APPENDAGES. of the cutis vera or Fig. 228. A. The g-eneral characters and the colourino" of the skin have ah'eady been described (pp. 4 to 7). The skin consists corium, and the cuticle or epidermis, and is possessed of numerous glands. a. The epidermis (Figs. 228, 230) con- sists of several layers of epithelial cells, those of the deepest layer being- more or less columnar in form, those of the middle layer shorter and polygonal, while those of the superficial layer are f
. The anatomy of the frog. Frogs -- Anatomy; Amphibians -- Anatomy. THE SKIN AND THE SENSE-ORGANS. I. THE SKIN AND ITS APPENDAGES. of the cutis vera or Fig. 228. A. The g-eneral characters and the colourino" of the skin have ah'eady been described (pp. 4 to 7). The skin consists corium, and the cuticle or epidermis, and is possessed of numerous glands. a. The epidermis (Figs. 228, 230) con- sists of several layers of epithelial cells, those of the deepest layer being- more or less columnar in form, those of the middle layer shorter and polygonal, while those of the superficial layer are flattened, very transparent, and horny. All the surfaces of these cells are serrated, the serrations being, however, with diffi- culty seen on the free surface of the super- ficial cells (Leydig). Each cell has a distinct nucleus ; in the deeper cells the nucleus is oval, broad, and rounded, in the superficial cells flattened and thin. The surface of the epidermis (Fig. 230) forms a very beautiful mosaic of flat cells, chiefly hexagonal in form, with pale, cen- tral, oval nuclei. Here and there two adjacent cells appear to enclose a semilunar space (Fig. 228 I)); these spaces are occupied by peculiar cells (goblet-cells, E. Schultze; mucous cells, Leydig), which do not belong to the superficial cells but the layer of cells immediately beneath the horny layer (Schultze, Pfitzner). The cells are rounded or flask-shaped, and closely resemble the epithelial goblet-cells or chalice-cells. According to Rudneff they open on the free surface by stomata ; this is, however, denied by Schultze and others. Vertical section througli the epi- dermis from the head of Raiia excuk'iita ; after F. E. Schultze. 600 times. A Horny layer. li Middle layer. C Deep layer. D Isolated Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resem
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