INTESTINAL NUTRITION IN THE OPOSSUM 349 



intestine and again the extreme girth was in the first limb at the 

 region of the first right-angle bend. The last three or four coils 

 of the small intestine were distinctly smaller than the others. 

 This great disparity in the caUber of the different parts of the 

 intestine was found to persist in specimens of at least several 

 weeks' age. 



The villi of the small intestine of the pouch-young are covered 

 by tall columnar cells with large centrally placed nuclei. A 

 delicately striated cuticle rests upon a distinct cement line and 

 terminal bars are very prominent. In the distal ends of the 

 cells are large granular strands and masses which vary con- 

 siderably in shape and size. The masses are located in a zone 

 which occupies about the middle third of the space between 

 the nucleus and the cuticular border of the cell. The distribution 

 of these granules may be more extensive, but distally there is 

 always a narrow strip of cytoplasm devoid of granules. These 

 cytoplasmic inclusions stain brilliantly with eosin, and with the 

 acid fuchsin of the Mallory stain. Iron hematoxylin brings them 

 out distinctly. After staining with alum-cochineal in toto, the 

 granular masses are faintly visible; following this stain with 

 gentian violet applied to the tissue after sectioning, the masses 

 become intensified but remain much paler than the nucleoli. 

 These granular aggregations, varying in shape and size, appear 

 in nearly all the cells of the villi and in some of the cells of the 

 intervillous spaces. The strands are made up of fine granules; 

 the larger masses are likewise composed of granules or consist 

 of a limiting border of granules enclosing a less densely stained 

 homogeneous interior. The ultimate round granules also vary 

 considerably in size; minute isolated ones may be seen between 

 the larger groups. Some of the cells are filled with a non-staining 

 substance so that they appep-r practically empty; a small amount 

 of protoplasm chngs to the nucleus and a few strands may 

 stretch across to the cell-membrane. Many other cells are 

 partially vacuolated; these occur more abundantly in the first 

 large coils of the intestine. The cells on the left side of the 

 villus shown in figure 18 are of this type. 



