Jeffries.] 222 [February 7, 



containing the nuclei. These for the most part are long and 

 have but one nucleolus. As a whole the horn cells do not stain 

 readily with carmine solution and but poorly with any water or 

 alcoholic solutions. They can, however, be easily stained by 

 placing the object, after treatment with alcohol in a benzole-eosin 

 solution. 



Kerbert describes a layer of cells between his granular layer 

 (Kornerschicht) and horn layer of polygonal cells with toothed 

 edges, though he says they are not true "Riffzellen." These cells 

 as forming a distinct layer are difficult to find and seem to be 

 only the oldest true horn-cells ; the toothed appearance being due 

 in part at least to the granules collected along their walls. 



The mucous layer which up to this time formed a very even 

 line has now become slightly irregular. The cells are the same 

 as before. Between the mucous and the horn cells are cells in 

 various steps of transition into horn-cells. 



Besides the several layers of cells described above, pigment 

 cells (figs. 9 nnd 16) have made their appearance in considerable 

 numbers in the mucous layer, and cells divided off from it, which 

 up to this time have not been very much modified, that is, turned 

 into granular or horn cells. Kerbert considers these pigment 

 cells, which he describes as quite branching, to be derived from 

 connective tissue pigment cells that wander from the mesoderm 

 into the epiderm. Accordingly he describes cells with their 

 branches in the epiderm and their bodies in the derm, others in 

 the epiderm and yet others in the derm. I have examined a 

 good many sections containing much pigment, but have been 

 unable with any power varying from 5 T ° to J^ T °-°- to find such half- 

 way cells. Pigment cells in the derm are to be seen, also blood 

 globules ; and branching patches of pigment apparently in cell 

 walls in the epiderm. These often appear to stand out into the 

 derm as figured by Kerbert. But if the focus of the glass be 

 properly adjusted the apparent membrane between the mucous 

 layer and the derm will be seen inside. The apparent projection 

 of the pigment cells into the derm would seem to be due to their 

 dark color. This makes them visable below the lighter cells in 

 focus, and hence, since the epiderm is often seen slightly slant- 

 wise, seem to project through into the derm. This pigment 

 whether it comes from epiderm or derm is the same as that in 

 feathers. 



