| OCR Text |
Show 352 MB. P. CHALMERS MITCHELL ON THE [May 7 of the intestine disposed in a fashion which, from the examination of a number of birds, I have found to be most instructive. The intestines were removed bodily from the abdominal cavity after division of the oesophagus and of tbe rectum in front of the cloaca. They were then placed on the table with the ventral side upwards, and with as little disturbance as possible the overlying folds were turned outwards. The duodeum (el) is a short loop enclosing the pancreas in the usual fashion. Then follows a very long small intestine (l-l) suspended at the circumference of a nearly circular expansion of the original straight mesentery running from the liver to the rectum. This loop of the intestine corresponds in position and arrangement to the anterior of the two enormous loops which compose the gut behind the duodenum in the Ostrich. It also corresponds to the five or six more specialized loops found in the intestine of Anatidae, but remains in what appears to be a more primitive condition. At the end of the first large loop the intestine passes into the large intestine and the caeca are attached at" the point of junction. The caeca in m y specimen were different from those of the G. chavaria described by Beddard (3), in that they were nearly equal in size and much more sacculated than in the figure given by Beddard. The right cascum was closely bound to the distal part of the great loop of the intestine running forwards along it. The left caecum was attached to the descending loop of the duodenum, and in the figure is represented as turned forwards along with that. The rectum, as in C. derbiana and Palamedea, w7as very long and wide, although not nearly so long relatively as in the Ostrich. I do not give the measurements of the parts of the intestine, as from m y own observations, and still more from the extended observations of Garrod, Beddard, and others, it seems that the amount of individual variation makes comparisons of little value. Attached to the free or primitive ventral side of the large loop of the intestine, and nearly in the middle of its length, was a small caecum (y), the remains of the original yolk-duct. From the point of this a short ventral mesentery with a thickened edge ran forwards towards the liver. In the Ostrich the remains of the yolk-sac lie in the same relative position, and I have found in that the remnant of a similar ventral mesentery. A large number of radial veins leave the large loop of the intestine and converge upon an elongated, much expanded, large tributary of the portal vein. This runs inwards in the middle of the circular mesentery opposite the yolk-sac diverticulum. It is joined by a branch from the right caecum and from the distal part of the loop ; next, by one from the left caecum, next by one from the duodenum. Another large vessel from the large intestine joins these vessels, and from their meeting-point the large mesenteric vein joins with a small splenic vein and runs forwards as the portal vein. I may mention that the disposition of these vessels is similar in the Ostrich, |
