548 



THE HUMAN EMBEYO. 



During the fifth week (Figs. 234, 235, and 236), the oeso- 

 phagus lengthens very greatly; the stomach in consequence 

 shifts backwards, and at the same time acquires its characteris- 

 tic shape (Fig. 236, Mg), and becomes placed across the body 

 instead of along it. The vitelline loop of the intestine (Fig. 

 234) passes out some distance beyond the body ; it lengthens 



'Us. 



a. 



FIG. 235. 



FIG. 236. 



FIG. 235. Outline figure of the alimentary canal of a Human Embryo, 

 estimated as thirty-two days old. The figure is drawn from the ventral 

 surface, and the cavity of the alimentary canal is alone represented, not 

 the thickness of its walls. (From His.) x 12. 



FIG. 236. Outline figure of the alimentary canal of a Human Embryo, 

 estimated as thirty-five days old. The figure is drawn from the ventral 

 surface, and the cavity of the alimentary canal is alone represented, not 

 the thickness of its walls. (From His.) x 10. 



Cc, caecum. C7, rectum. Dd, duodenum. Ds, yolk-stalk. gl>, gall bladder. Lbg, 

 bile-duct. Lg, lung. Mg, stomach. P, pancreas. 



considerably, and becomes at the same time twisted on itself. 

 Before the end of the week, the tubular yolk-stalk (Fig. 235, Ds) 

 separates from the intestine, although detached portions of the 

 tube may persist along the yolk-stalk for some time longer. 

 The csecuni, Cc, arises during the fifth week as a diverticulum 

 from the distal limb of the vitelline loop, not far from the point 

 of attachment of the yolk-stalk. 



