SPLANCHNOLOGY. 199 
creatic duct commences at the small end, and extends to the large, receiving 
numerous branches on each side. It generally joins the ductus choledochus 
in asmall dilatation just before the duodenal opening ; a second duct some- 
times opens directly into the duodenum. An accessory gland, called the 
lesser pancreas, is sometimes found attached to the head of the pancreas. 
The pancreatic juice is mixed with the biliary in the duodenum, to separate 
chyle from the chyme of the food. Its especial office, from recent investi- 
gations, appears to lie in the assimilation of fats. 
9. THE PertroNazuUM. ‘The peritonzum is the largest serous membrane 
in the body, investing the viscera of the abdomen, much as those of the 
thorax are embraced by the pleura. The peritonzeum is a closed sac, and 
when opened, presents a continuous surface, which may be traced through- 
out the whole extent without interruption. The different folds which the 
peritonzeum forms in its course are mainly the lesser omentum, the great 
omentum, the splenic omentum, the colic omentum, the appendices epi- 
ploicz, the mesentery, meso-coecum, and meso-rectum. The relations of 
the peritonzum in the different parts of its course will be best understood 
by reference to pl. 130, jig. 9. 
Proceeding from the umbilicus, ', the peritonzeum passes along the inside 
of the anterior abdominal wall, *; then bending backwards, it lines the 
inferior surface of the diaphragm, *, forming on it the suspensory ligament, 
*, of the liver, °; it passes below the diaphragm over the liver, and coats 
its upper surface, °, the gall bladder, *, and a portion of the lower surface 
of the liver. From the liver it passes to the stomach, and forms, °, the 
anterior lamina of the lesser or gastro-hepatic omentum, and passes from 
the stomach to the spleen as the anterior lamina of the gastro-splenic liga- 
ment. The peritoneum next bends back on itself from the diaphragm in 
the form of a sac (saccus epiploicus), the opening, *°, to which is known as 
the foramen of Winslow. The two laminz of the gastro-hepatic omentum 
separate at the lesser arch of the stomach, ™, to inclose this organ, the 
posterior layer giving a serous covering to its back part, and the anterior to 
its fore part; they then touch each other again, ”, along the great arch of 
the stomach, and being joined by the peritonzeum from the spleen and the 
splenic vessels, descend to the lower part of the abdomen under the name 
of the gastro-colic or the great omentum, *. This then turns on itself 
‘and ascends obliquely backwards to the arch of the colon, along the convex 
edge of which its laminz separate to inclose this intestine, “, and its 
vessels. Along the concave edge of the colon these laminz again unite, 
**, to form the transverse meso-colon which passes backwards to the spine. 
Opposite the duodenum, “, this process separates into an ascending and 
descending layer, between which the inferior division of the duodenum 
lies. The ascending layer covers the pancreas, ”, and proceeding to the 
back part of the right lobe of the liver, becomes continuous with the peri- 
tonzeal layer, “, of this viscus. The descending layer, ”, of the transverse 
meso-colon expands in each lumbar region, in which it attaches the lumbar 
portion of the colon by a duplicature called the right and left lumbar meso- 
colon; it is thence reflected forwards over the small intestines, **”, and 
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