OF THE INTESTINES. 119 



" The discharge is facilitated by the absence of transverse rugae, 

 and especially by the great quantity of mucus at the extremity 

 of the bowels." 



The alimentary canal always contains gaseous substances, 

 which, being chiefly disengaged from its contents, must vary at 

 different parts of the canal. These serve the important purpose 

 of gently causing the canal to open progressively for the advance 

 of soft or solid contents. 



stimulates it to discharge them. Dr. O'Beirne, in his very original work, argues 

 successfully against this, 1st, from the inconvenience to the bladder and the con- 

 stant irritation of the sphincter ani, were accumulation to occur there, so that the 

 rectum is ill circumstanced for accumulation, whereas the caecum and colon 

 really appear constructed for receptacles. 2d, The sigmoid flexure is a great 

 depot for faecal matter, and therefore a free passage at all times into the rectum 

 is unlikely. 3d, Great force is usually required to force injections up the rectum, 

 as if it were naturally contracted and close. 4th, The finger or an instrument 

 introduced into the rectum is rarely soiled by fasces. 5th, Adhesions within the 

 rectum have often been found, but seldom or never in the other intestines, and they 

 must require an empty condition of the cavity for the necessary contact of the 

 sides. 6th, After division or destruction of the lower sphincter of the anus, 

 the fasces are generally retained as usual. 7th, He has examined the rectum 

 with a long tube in many healthy persons several times a day, and never found 

 faeces in it. Besides the muscular fibres possessed by the rectum in common 

 with the colon, it has strong fleshy fibres, circular and longitudinal, and it alone 

 receives nerves of sense and motion from the spinal marrow. 



Dr. O'Beirne considers, also, that an accumulation naturally occurs in the 

 caecum as well as in the colon, from the great acuteness of the angle at which the 

 ileum enters the caecum ; the greater capacity of the caecum than of either the 

 ileum or colon ; the course of the colon against gravity ; the necessity of the 

 caecum being filled before it can be excited to or supported in an expulsive 

 effort; and the distention of the colon all the way from the caecum to the sigmoid 

 flexure by gas, which prevents the ascent of the faeces from the caecum till it 

 escapes from the lower bowel. He conceives that the whole contents are trans- 

 ferred at once : and as, at the time of defecation, there is usually one mass in the 

 sigmoid flexure and one in the caecum, that the amount of the two is the evacu- 

 ation; and as two distinct acts of expulsion are always required before the 

 bowels in health are sufficiently freed, that the capacity of the rectum may be re- 

 ceived as the measure of that of the caecum. When he has had every reason to 

 believe that no faeces were in the sigmoid flexure, from a hollow bougie passed 

 into it remaining unsoiled, flatus escaped ; and, on passing the instrument again 

 in five minutes, its upper extremity has been coated with faeces, and a solid evacu- 

 ation soon occurred. 



I think that the sympathy between the stomach and the large intestines, when 

 these are charged, deserves notice. When the intestinal contents have accumu- 

 lated, the repletion of the stomach by even a moderate meal excites the lower 

 portion of the canal to discharge its contents, so that a meal at such a time causes 

 a desire for relief, and the more as the meal is greater, 



