TORSION OF THE DOUBLE COLON 249 



second colon, the material is becoming more fluid, wliile at the 

 pelvic flexure the contents are invariably in a liquid, pea-soup- 

 like condition, and the particles of which tliey are composed 

 are not readily recognized. In the iliird colon the material 

 becomes firmer, but only slightly so, and bubbles of gas are 

 being constantly given off from its surface. In the fourth 

 colon, the entire ingesta are like thick soup, and the material 

 composing them is in a finely comminuted condition, the 

 surface being covered with gas bubbles. For the first foot or 

 so of the single colon this condition is maintained, when quite 

 suddenly the contents are found solid and formed into balls. 

 The remarkable suddenness of this change is invariable in a 

 state of health, and indicates either most active absorption or 

 that the contents are subjected to great compression. The 

 entire contents of the colon are 3-ellow in colour or yellowish- 

 green, becoming rapidly brown or olive green on exposure to 

 the air, the colour being due to the chlorophyll of the food. 

 The contents of the colon arc normally alkaline throughout ; 

 we once, however, found them acid.' 



Movements of the Intestines. — ' The movements of the 

 intestines are brought about by the involuntary muscle com- 

 posing its wall. This muscle in the small intestines is 

 arranged in two sheets in a circular and longitudinal manner, 

 while in the large intestines narrow bands of pale muscle of 

 considerable length take the place of the ordinary longitudinal 

 laj'er, and may be found on all parts where the tube is saccu- 

 lated ; in fact, one function of the bands is to bring about the 

 sacculated condition of the canal, an important arrangement 

 whereby economy of space is effected with no loss of surface. 



' The sacculated condition of the double colon is confined 

 principally to the first, second, and foiu'th portions. The third 

 portion, especiallv at the pelvic flexure, is free from saccula- 

 tions, and the fourth portion is not so liberally puckered as 

 the first and second. On the first colon there are four bands ; 

 on the second colon there are also four, three of which dis- 

 appear at the pelvic flexure ; on the third portion there is only 

 one band ; while on the fourth colon there are three (see 

 Figs. 17 and 21). In the large intestines the longitudinal layer 

 of fibres is confined to the muscular bands, so that the great 



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