. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 368 STOMACH AND INTESTINE. which generally concedes to the contents of the large intestine a long delay, and a slight movement over a large absorptive surface, would still be quite capable of effecting their rapid and vigorous expulsion, when required to do so. Nay, more, since much of this ex- pulsive act seems, as it were, removed from the sacculi themselves, and concentrated in the bands around them, we may conjecture that the mechanism of these latter contrac- tile masses is also specially concerned in the nervous pa
. The cyclopædia of anatomy and physiology. Anatomy; Physiology; Zoology. 368 STOMACH AND INTESTINE. which generally concedes to the contents of the large intestine a long delay, and a slight movement over a large absorptive surface, would still be quite capable of effecting their rapid and vigorous expulsion, when required to do so. Nay, more, since much of this ex- pulsive act seems, as it were, removed from the sacculi themselves, and concentrated in the bands around them, we may conjecture that the mechanism of these latter contrac- tile masses is also specially concerned in the nervous part of the process. At least, it is not impossible, that the irritation or stretching of these two sets of muscles (which can be effected only by the general distention of the calibre of the tube, and not by the local dis- tention of its cells) may constitute the im- mediate stimulus of the evacuation of the whole large intestine, or of any particular segment. The mucous membrane of the colon may be described as only differing from that of the small intestine in the fact that it is somewhat thicker, and quite devoid of villi. Its more numerous tubes are about one-third longer than those of the small intestine; and their diameter seems to be, in general, still more increased. Its solitary follicles are also more numerous, and of larger size. And the depressions which mark the site of each on the internal surface of the bowel are here represented by a distinct pit; which leads by vertical, or even somewhat divergent sides, to the follicle that occupies its base. But the secretions of these structures, and the cell- growth which lines them, do not present any noticeable difference from their analogues in the small intestine. The rectum (r, fg. 274-. ; r 1, r 2, r 3, fg. 276.) (formerly straight gut, Eng. ; Mastdarm, Germ.), which intervenes between the sig- moid flexure of the colon («) and the anus («), forms the terminal segment of the large intestine. It has received the abov
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