CHAP. XII.] THE CONTENTS OF THE COLON. 449 



thelium cells present, in a very characteristic manner, large numbers 

 of ' goblet-cells.' 



The muscular coat exhibits a peculiarity in the arrangement of its 

 bundles of fibres, especially of those of its longitudinal coat, which 

 are ' gathered up into three thickened bands or bundles, being very 

 thin elsewhere. These bands, moreover, are shorter than what may 

 be called the natural length of the intestine, so that the tube instead 

 of being, as in the small intestine, of fairly uniform bore, is puckered 

 up into sacculi more or less divided by the three bands into groups of 

 three. This sacculated arrangement answers much the same purpose 

 as the arrangement of valvulse conniventes in the small intestine. 

 The circular muscular layer is thicker in the middle or bellies of the 

 sacculi than at the puckers, where it is very thin... As the sigmoid 

 flexure passes into the rectum, the three bands. of the longitudinal 

 muscular layer spread out and become once more a uniform layer; 

 and with this change the sacculation disappears. This longitudinal 

 coat is continued to the anus, where it ends abruptly. The circular 

 coat at its termination at the anus is developed into a distinct ring, 

 the internal sphincter... Down to the margin of the anus the mucous 

 membrane retains the characters of the large intestine, glands being 

 still present; it then abruptly puts on the epiblastic characters of 

 the epidermis 1 .' 



SECT. 2. THE CHARACTERS OF THE INTESTINAL CONTENTS AS THEY 

 PASS FROM THE ILEUM INTO THE LARGE INTESTINE. 



As the contents of the ileum pass into the colon they are more or 

 less diffluent, possess a yellowish colour, and are almost or quite 

 devoid of odour. From the admirably studied, and almost unique 

 case of Macfadyen, Nencki and Sieber 2 , in which a fistula of the 

 ileum existed at its very junction with the colon, it would appear 

 that the contents of the small intestine are continually passing into 

 the large, though the flow is less during the night, apparently in 

 consequence of the abstention from food. Macfadyen, Nencki and 

 Sieber determined how long ingested bodies occupied in reaching the 

 caecum, and they found the time to vary within wide limits. When 

 their patient ate green peas, the first of these appeared at the fistulous 

 aperture, in one case 2J, and in another 5J hours afterwards. In the 

 first case, the last of the green peas were discharged 14 hours, in the 

 second case 23 hours, after they had been swallowed. The rate with 

 which the intestinal contents travel towards, and the time occupied 

 in reaching, the ilio-caecal valve depend upon the consistence of the 

 intestinal contents and upon the intensity of the intestinal move- 

 ments. 



1 M. Foster, A Text-Book of Physiology, 5th ed. Part II. comprising Book n. pp. 

 450 and 451. Macmillan, 1889. 



2 Macfadyen, Nencki and Sieber, ' Ueber die chernischen Vorgange im menschlicken 

 Diinndarm,' Archiv f. exp. Path. u. Pharm., Vol. xxvm. (1891), p. 311 et seq. 



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