THE ORGANS OF THE INNER GERM-LAYER. 305 



upper [anterior] part, which contains the stomach, liver, duodenum, 

 and pancreas, and a lower part, holding the small intestine. 



Thus embryology explains the striking condition of the duodenum, 

 which, in order to pass from the upper to the lower space and to 

 become continuous with the small intestine, passes underneath [dorsal 

 to] the transversely outstretched mesocolon (figs. 165 and 167 du). 



Also in the case of the suspensorium of the coBcum, and of the 

 ascending and descending arms of the colon, there occurs a more or 

 less extensive concrescence with the peritoneum of the wall of the 

 trunk. Therefore in the adult the parts of the intestine named 

 sometimes lie with their posterior wall broadly in contact with the 

 body-wall ; sometimes they are supported by a broader or narrower 

 mesentery. 



There still remain to be described the important changes of the 

 bursa omentalis, the development of which during the first months of 

 embryonic life we have already (p. 299) become acquainted with. 

 The bursa is distinguished, first, by a very considerable growth, 

 and, secondly, by the fact that it fuses with neighboring organs at 

 various places. In the beginning it reaches only to the greater 

 curvature of the stomach (figs. 165, 166), to which it is attached; 

 but even from the third month onward it enlarges and lays itself over 

 [ventral to] the viscera which lie below the stomach, at first over the 

 transverse colon (fig. 167 A gn l , gn 2 ), then over the whole of the 

 small intestine (fig. 1'67 A gn 3 ). The bursa consists, as far as it has 

 extended downwards, of two lamellae, which lie close to each other, 

 separated by only a very narrow space, and are continuous at their 

 lower margin. Of these the more superficial, the one which is nearer 

 to the ventral wall of the belly, is attached to the greater curvature 

 of the stomach (gc) ; the posterior [dorsal] lamella, which lies upon 

 the intestines, is originally attached to the vertebral column and here 

 encloses the main part of the pancreas (figs. 167 A p and 166 p). In 

 the case of many Mammals (Dog) the bursa omentalis remains in 

 this condition. In Man it begins as early as the fourth month 

 to undergo fusions (fig. 167 B}. On the left side jof the body the 

 posterior lamella reposes on the posterior wall of the body over a 

 large extent of surface, and fuses with it (gn*), so that its line of 

 attachment to the vertebral column moves laterad up to the origin 

 of the diaphragm (lig. phrenico-lienale). Farther down it glides over 

 the upper [anterior] surface of the mesocolon (msc) and over the- 

 transverse colon (ct) ; it becomes fused with both of them, with the 

 former as early as the fourth embryonic month. At the time of 



