1014 THE DIGESTIVE SYSTEM. 7" 
most numerous in the ileum, particularly in its lower part, where they usually 
assume an oblong shape; in the lower haif of the jejunum they are small, circular, 
and few in number; in its upper part they are rare; and, although their presence 
has been noted in the lower portion of the duodenum, they may be said to be 
as a general rule absent from this division of the intestine. 
The valvule conniventes stop at the margins of Peyer’s patches, and are not continued across 
them ; but villi are found on the surface of the patches, in the intervals between the ly mphoid 
nodules. 
The chief bowel lesion in typhoid fever is found in Peyer's patches and the solitary glands. 
When the surface of a Peyer’s patch from a child’s intestine (in which these structures are 
particularly well developed) is carefully examined, it is seen to be made up, not of a series of 
separate, rounded nodules grouped together, but rather of a number of wi avy, irregular, and 
branching ridges connected with one another by cross branches (Fig. 686), the whole recalling i in 
miniature, the appearance of a raised map of a very mountainous district in which the chief 
chains run irregular courses, and are joined to one another by connecting ridges. ; 
Small patches, intermediate in form between solitary glands and Pey ers pate hes, and consist- 
ing of two or three lymphoid nodules, are also usually present. 
THE SMALL INTESTINE. 
The small intestine is the portion of the digestive tube which is placed 
between the stomach and the beginning of the large intestine. It commences at 
the pylorus, where it is continuous with the stomach, and ends at the ileo-cecal 
valve by joining the large intestine. It occupies the greater portion of the 
abdominal cavity below “the liver and stomach (Fig. 671), and is found in 
the umbilical, hypogastric, and both lumbar regions; also, but to a less extent, in 
the other regions of the abdomen, and in the pelvie cavity. 
In length, the small intestine usually measures over 20 feet. According to 
Treves, it is 224 ft.in the male, 23 in the female, whilst Jonnesco gives the average 
length at 24 ft. 7 ins., or 7} metres. In form it is eylindrical, with a diameter 
vary ing from nearly two inches (47 mm.) in the duodenum to a little over an inch 
(27 mm.) at the end of the ileum; there is thus a eradual diminution in its 
size from the pylorus to the ileo-caecal valve. J 
This portion of the digestive tube is divided more or less arbitrarily into three 
parts (Fig. 636)—namely, the duodenum, constituting the first eleven inches, dis- 
tinetly marked off from the rest by its fixation and the absence of a mesentery ; the 
jejunum, which comprises the upper two-fifths, and the ileum, the lower three-fifths 
of the remainder. The two latter parts pass imperceptibly into one another, 
and the line of division drawn between them is entirely artificial; however, 
if typical parts of the two—namely, the beginning of the jejunum and the 
end of the ileam—be selected, they differ so much in size and in the appearance 
presented by their ining mucous membrane, that they can be distinguished from 
one another without difficulty. 
Both the jejunum and ileum are irregularly disposed in the form of crowded 
loops or coils (Fig. 670) which are connected to the posterior abdominal wall by a 
great fan-shaped fold of peritoneum, containing their vessels and nerves, and 
known as the mesentery. This is of such a length that the coils are able to move 
about freely in the abdominal cavity, and consequently the position occupied by 
any portion of the tube, with the exception of the beginning of the jejanum and 
the ending of the ileum, can never be stated with cer tainty. Nevertheless, it 
may be said that, in general, the jejunum occupies the upper and left portions of 
the cavity below the stomach, the ileum the lower and right divisions, its terminal 
part almost always lying in the pelvis, just before it jos the large gut. 
The small intestine is relatively longer in the child than in the adult ; at birth it is to the total 
height of the child as 7 to 1, whilst in “the adult. the proportion is as 4 tol. Notwithstanding 
Treves’ results, it is genet ally held that the small gut is relatively longer in the male than the 
female. 
It should perhaps be added that in formalin-hardened bodies the small bowel rarely meastires 
more than 12 or 13 feet in length. Similarly its diameter is often reduced in places to 3 or 
inch (125 to 18-7 mm.), although the greater part of the gut may retain its usual width; Te 
narrow parts have apparently heen fixed in a state of contraction. 
