The laws and mechanics of circulation, with the principle involved in animal movement . ownward and backward against the rectum (i?), which can-not escape and must endure the pressure, at the same timecontracting energetically for assisting the action, while thesphincters expand simultaneously for reducing resistance, asalso for obviating strain and rude friction in the parts, otherwiseinevitable. It is simply perfect. As will be seen, the ligamentis carried downward, and is no longer upon the plane it occu-pies in the erect position or toward the anterior abdominalwalls (Fig. 120, 31, E). And
The laws and mechanics of circulation, with the principle involved in animal movement . ownward and backward against the rectum (i?), which can-not escape and must endure the pressure, at the same timecontracting energetically for assisting the action, while thesphincters expand simultaneously for reducing resistance, asalso for obviating strain and rude friction in the parts, otherwiseinevitable. It is simply perfect. As will be seen, the ligamentis carried downward, and is no longer upon the plane it occu-pies in the erect position or toward the anterior abdominalwalls (Fig. 120, 31, E). And by thus pulling the mesentericpiston with great force down upon the bladder and rectum,together with the action in the viscus, the contents are ex- CONCENTRATING FORCE IN THE PELVIC VISCERA. 309 pelled. In short, nothing could be more admirable than thearrangements which obtain for increasing pressure in thepelvic excavation commensurate with the functions in theseorgans, the same remark applying for every stage in develop-ment. Thus in the quadruped the lumbar vertebrae are flexed. Fig. 134.—Longitudinal Section of the Abdomen, showing position of the mesenteryduring expulsion of waste products. M, middle of mesentery ; I, I, coils of smallintestine ; E, anterior abdominal wall ; B, bladder ; R, rectum ; C, colon ; S,stomach ; L, liver ; D, diaphragm ; Q, duodenum ; P, pancreas. by incurvating them upward, which is done by contractingthe recti and obliqui, as in man, the muscles upon the dorsalsurface at the same time expanding or elongating pari passuwith this movement. Then the diaphragm is contracted forshortening the longitudinal axis ; finally, the transversalesand internal oblique muscles are energetically contracted for :*10 CONCENTRATING FOllCE IN THE PELVIC VISOKRA. shortening the transverse axis and compelling the mesentericpi stun into the pelvic excavation. The action is studied to great advantage in the dog and cat,in which the excrement is hard, and Unusual fo
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Keywords: ., bookcentury1800, bookde, booksubjectblood, booksubjectrespiration
