.380 THE LIVER. 



is thrown into wrinkles during the closed state of the orifice, is covered 

 Avith numerous papillae, and is provided with hairs and sebaceous 

 follicles. 



The lower end of the rectum and the margin of the anus are, more- 

 •over, embraced by certain muscles, which serve to support the bowel, 

 and to close its anal orifice. These muscles, proceeding from within 

 outwards, are, the internal sphincter, the levatores ani, the coccygei, and 

 the external sphincter. The three last muscles have already been 

 described. 



The internal sphincter muscle (sphincter ani internus) is a muscular 

 ring or rather belt, surrounding the lower part of the rectum, an inch 

 above the anus, and extending over about half an inch of the intestine. 

 It is two lines thick, and is paler than the external sphincter. Its fibres 

 ^re continuous above with the circular muscular fibres of the rectum, 

 and, indeed, it consists merely of those fibres more numerously developed 

 than elsewhere, and prolonged farther down than the external longitu- 

 dinal fibres. 



Kohli-causch describes a thin stratum of fibres between the mucous membrane 

 and the internal sj^hincter, these fibres having a longitudinal direction. Henle 

 thinks this is nothing- more than the stratum of fibres belonging to the proper 

 mucous coat ; but Kohlrausch gives it a distinct name, the sustentator tunicaj 

 mucoste. (Kohli-ausch, Anat. und Phys. d. Beckenorgane. Leipzig, 185-1.) 



Ellis further describes a thin layer of involuntary muscle "with radiating fibres 

 which pass from the submucous tissue inside the internal sphincter to end in the 

 subdermic tissue outside. (Illustrations of Dissections. London, 1865. P. 243.) 



THE LIVER. 



The liver is an important glandular organ, very constant in the 

 animal series, being found in all vertebrate, and, in a more or less de- 

 veloped condition, in most invertebrate tribes. It secretes the bile, 

 and appears to act, in a manner as yet imperfectly understood, upon the 

 blood which is transmitted through it. Moreover there is formed in 

 its texture a starchy substance (glycogen), very easily converted into 

 sugar. 



The liver is the largest gland in the hodj, and by far the most bulky 

 of the abdominal viscera. It measures about 10 or 12 inches trans- 

 versely from right to left, between 6 and 7 inches from its posterior 

 to its anterior border, and about oh inches from above downwards where 

 thickest, which is towards the right and posterior part. The average 

 bulk, according to Krause, is 88 cubic inches ; according to Beale, one 

 hundred. The ordinary weight in the adult is between 50 and 60 

 ounces. 



According to the facts recorded by Reid, the liver weighed, in 43 cases out of 

 82, between 48 and 58 ounces in the adult male ; and in 17 cases out of 36, 

 between 40 and 50 ounces in the adult female. It is generally estimated to be 

 equal to about l-3Gth of the weight of the whole body ; but in the foetus, and 

 in early life, its proportionate weight is gTeater. 



The specific gravity of the liver, according to Ki-ause and others, is between 

 1'05 and 1-06 : in fatty degeneration this is reduced to 1*03, or even less. 



The liver is solid to the feel, and of a dull reddish-brown colour, with 

 frequently a dark-purplish tinge along the margin. It has an upper 

 surface smooth and convex, and an under surface, which is uneven and 



