vrn 



LIVER 



133 



by a narrow band of unstriped muscle, the muscularis 

 mucosa, formed, like the main muscular layer, of an 

 outer layer of longitudinal (/. m. m) and an inner of 

 circular (c, m. m) fibres. 1 



The Pancreas. Sections of this gland (Fig. 41) sho\> 

 it to be made up of microscopic masses or lobules (/), 

 each of which consists of a cluster of gland-cells en- 

 closing a very narrow central space. The cavities of 

 adjacent lobules communicate with one another and 



B 



FIG. 41. A, small portion of a section of the Frog's pancreas (x about 300) ; B. 



diagram showing the connection between the lobules and ducts. 

 c. connective-tissue covering the lobules ; d. duct ; /. lobules ; nu. nuclei. 



open into tubes or ducts (d) lined with epithelium, 

 which join with one another and finally discharge into 

 the bile-duct as it traverses the pancreas (p. 70). The 

 pancreas is distinguished as a racemose or grape-bunch 

 gland : the duct is comparable to the branched stalk 

 and the lobules to the grapes. 



The Liver. Sections of the liver show it to be made 

 up of innumerable large, polyhedral cells (Fig. 42, hp, c), 

 arranged in columns, and bounding extremely fine 



1 A very thin muscularis mucosse is also present in the intes- 

 tine ; (compare Fig. 39, B). 



