ANATOMY OF THE THKEE-TOED SLOTH. 167 



The small isolated piece of pancreas has its separate duct and 

 papilla. 



Histology. 



When the pancreas is examined under the low power ( x 180) 

 it is seen to possess a loose, open texture. The glandular alveoli 

 are either isolated or aggregated loosely into groups, and all are 

 supported by delicate connective tissue. The ducts may be in- 

 visible when the cells are loaded with granules, but they appear 

 as clear circular central areas when the cells are not so loaded. 

 Multinucleated areas of different kinds are seen. 



Under the high power ( x 480) the gland-cells are seen to 

 contain granules of different sizes and different degrees of coarse- 

 ness, and the bases of the cells are the most granular parts. The 

 nuclei are circular, laige, and present well-marked granules and 

 networks ; in some the granules predominate, but in others the 

 reticulum is the chief feature. 



The multinucleated areas differ greatly in appearance, but can 

 be arranged in three groups : — 



1. Many nuclei and little surrounding protoplasm. 



2. Many nuclei with much protoplasm which stains faintly. 



3. Many nuclei with much protoplasm which stains deeply. 



In all, the nuclei are of varying shapes and sizes. 



The connective tissue may appear as delicate strands round the 

 alveoli, or it may form a strong network within the meshes of 

 which the alveoli are contained. The mesh work is also cellular, 

 and the nuclei are circular or long and narrow. 



The Liver. 



I have nothing to add to existing accounts of the macroscopic 

 appearances. 



Histology (Plate IV". 0). 



Under the low power it is seen how the cells have the usual 

 arrangement in columns, but each cell has golden-yellow pigment 

 granules in the centre. There appears, therefore, to be a yellow 

 axis running along the centre of the column, for all the cells are 

 filled from end to end with the pigment. 



The high power reveals how a few cells are destitute of pig- 

 ment, so pigmented and non-pigmented cells are to be described. 

 The unpigmented cells, which are in the minority, are cubical, 

 hexagonal, or pentagonal in shape. Their protoplasm is faintly 

 granular, and their nuclei are large, round, and granular. The 

 pigmented cells cannot have their limits so easily defined, for the 

 pigment granules are tightly packed and obscure their contiguous 

 walls. The granules are coarse or fine and form a central axis, 

 but they never obscure the large, spherical, granular nucleus of 

 the cell. The axis is bordered on either side by the cytoplasm of 

 the cell which is finely granular, but the granules do not consist 



