. The anatomy of the frog. Frogs -- Anatomy; Amphibians -- Anatomy. THE ALIMENTARY TEACT. 293 by an abrupt curve at its anterior end. The large intestine is the widest part o£ the alimentary canal, is thin-walled, and diminishes in width towards its hinder end, where it opens into the cloaca above the opening" of the bladder. b. [Minute structure. (i) The serous coat resembles that o£ the small intestine, etc. (2) The muscular coats resemble those of the small intestine, but are thinner ; the longitudinal layer is, however, proportionally thicker (Wiedersheim). (3) The submucous coat (Fig
. The anatomy of the frog. Frogs -- Anatomy; Amphibians -- Anatomy. THE ALIMENTARY TEACT. 293 by an abrupt curve at its anterior end. The large intestine is the widest part o£ the alimentary canal, is thin-walled, and diminishes in width towards its hinder end, where it opens into the cloaca above the opening" of the bladder. b. [Minute structure. (i) The serous coat resembles that o£ the small intestine, etc. (2) The muscular coats resemble those of the small intestine, but are thinner ; the longitudinal layer is, however, proportionally thicker (Wiedersheim). (3) The submucous coat (Fig. 192) resembles that of the small intestine in its general structure ; the portion Ijang immediately beneath the mucous membrane (£) is denser in structure. This layer has no 3[?/fic?/laris mucosa. (4) The mucous coat [A) is a simple layer of large, columnar, epithelial cells, with large oval nuclei. The cells have a hyaline free border, but this possesses no stri- „. ation. The mucous membrane is usually described as possessing numerous simple -B^ follicles (glands of Lieberkiihn) ; in those specimens which I have exa- mined they have been entirely absent (Figs. 192, 193). At six to eight points in a transverse section of a rectum moderately distended the sub- mucous coat is thinner, and so throws the mucous coat into slight, longitudinal grooves ; but these do not in the least resemble the glands of Lieberkiihn. (5) The epithelium possesses goblet- or chalice-cells (Hoffmann), the number of which probably depends upon the period of the year and the state of digestion. In the rectum, from which the section for the figures 193 and 193 were cut, not one goblet-cell was found in a complete series of sections. If the rectum be contracted, the mucous membrane is thrown into longitudinal Transverse section of large intestine of liana eseulenta ; the mucous mem- brane thrown into longitudinal folds in consequence of the organ being contracted. Arteries injected with car
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