THE LARGE INTESTINE. 343 



in proportion to that of the whole body is as 1 : 36 ; in the 

 former, as 1 : 18. The physiological significance of the liver 

 during embryonic life — which is very great — depends espe- 

 cially on the part it plays in the formation of blood, and 

 less on its secretion of bile. 



From the gall-intestine, immediately behind the liver, 

 grows another large intestinal gland, the ventral-salivary 

 gland, or pancreas. This organ, which occurs only in 

 Skulled Animals, also develops as a hollow sac-shaped 

 protuberance of the intestinal wall. The intestinal-glan- 

 dular layer of the latter sends out branching shoots, which 

 afterwards become hollow. The ventral-salivary gland, just 

 like the salivary glands of the mouth, develops into a large 

 and very complex gland shaped like a bunch of grapes. 

 The outlet of this gland (ductus pancreaticus), through 

 which the pancreatic juice passes into the gall-intestine, 

 seems to be at first simple and single ; afterwards it is 

 often double. 



The last section of the intestinal tube, the terminal 

 intestine or large intestine (epig aster), in mammalian 

 embryos, is, at first, a very simple, short, and straight tube, 

 opening posteriorly through the anus. In the lower Ver- 

 tebrates it retains this form throughout life. In Mammals, 

 on the other hand, it grows to a considerable size, coils, and 

 differentiates into different sections, of which the foremost 

 and longest is called the colon, the shorter and hinder the 

 rectum. At the commencement of the former a valve 

 (valvula Bauhini) forms, which divides the large intestine 

 from the small intestine ; behind appears a pouch-like 

 protuberance, which grows, larger and becomes the blind- 

 intestine (coecum) (Fig. 288, v). In plant-eating Mammals 



38 



