modern craze for patent aperient medicines, favours the production of disease in the colon.

This book is founded upon the Essay which was awarded the Jacksonian Prize for 1909 by the Royal College of Surgeons. In order to make it a practical and useful textbook, it has been necessary to make several additions to the original essay, and to condense some of the chapters dealing with rare conditions of the bowel. The earlier chapters are devoted to the anatomy and physiology of the colon, both in health and disease. The subject of diagnosis has been very thoroughly discussed, this being the factor presenting the greatest difficulty in dealing with disease when it attacks the colon. Special attention also has been paid to the effect of adhesions, and to chronic constipation and obstruction in their various forms. The different varieties of colitis are fully considered, as also are pericolitis and

cancer.

The closing chapters of the book are devoted to a description of the various operations which may be performed on the colon.

I have to offer my best thanks to those friends who have kindly lent me blocks or illustrations.

IO, CAVENDISH PLACE, W.,

May, 1910.

P. L. M.

DISEASES OF THE COLON.

CHAPTER I.

THE ANATOMY AND
DEVELOPMENT OF THE
THE COLON

THE ANATOMY OF THE COLON.

IN man, the colon starts in the right lower part of the abdomen, and passes up towards the liver, then across towards the spleen, and then downwards to reach the rectum. In most carnivorous animals, however, the cæcum lies under the liver, and the colon passes across and then down, having the shape of the letter L inverted, the colon thus being much shorter relatively than in man. In man the commencement of the colon forms a dilated pouch, called the cæcum, into which the small bowel opens by a valve-like opening. The caput coli may be looked upon almost as a second stomach, and Prof. Keith has pointed out that it corresponds both embryologically and anatomically to the stomach as regards function. It has the same relationship to the large bowel that the stomach has to the small bowel.

In some animals the cæcum or caput coli is the main organ of digestion; while in others, as in man, the stomach has this function.

In the iguana, the orang-utang, and some monkeys, the caput coli forms a separate viscus, with a valve between it and the ileum, and also between it and the colon (Fig. 1).

In the tapir, although there is no such perfect valve as exists in the iguana, there is a circular fold forming a definite division between the caput coli and the remainder of the colon.

In fishes there is no distinction into small and large bowel. In some animals, instead of the caput coli being dilated to form a cæcum, there are pouches connected with the large bowel which

doubtless act similarly. Thus in the hyrax there are three so-called cæca, two paired and one single.

In the lemur (Perodicticus patto) a very curious arrangement exists. The colon is folded back upon itself twice, the folds being connected by a delicate mesentery.

In most animals the descending colon joins the rectum as a more or less straight tube, and there is no coil like the sigmoid. flexure in man.

The colon extends from the ileocæcal valve to the rectosigmoidal junction. The exact position of this latter point has been rather uncertain, different writers having taken different points for the junction between the pelvic colon and the rectum; the correct anatomical point, however, is at the

Fig. 1.-Diagrammatic representation of the Cæca of A, Iguana and Orang-utang;
B, Tapir; and C, Hyrax.

position of what has by some observers been called the sigmoidorectal sphincter. There is at this point a distinct fold, or narrowing of the bowel lumen, which can easily be seen if the bowel is examined with the sigmoidoscope. This point corresponds roughly to the point at which the bowel becomes fixed.

The length of the colon varies considerably in different. subjects. The average length is about 22 inches. Mr. Lockwood, from a study of dissecting-room subjects, found the usual length to be 22 inches, the longest he met with being 28 inches. Amussat found that it varied from 18 inches to 2 feet. The average length of the ascending colon is 8 inches, and that of the descending colon 8 inches.