86 FEATHERS. 



tema of the cells of the pith of the feather is supplied by the 

 nearest contiguous substance provided with vessels, that is, by 

 the so-called matrix. In the young feathers of the hen, how- 

 ever, I found a layer of very small, extremely pale, round cells 

 without nuclei, — a sort of imperfect epithelium, — between 

 the matrix and the granulous cytoblastema, so that not even 

 so much as an immediate contact exists between the latter and 

 the organized substance. 



The cortical substance of the shaft of the feather is a 

 fibrous structure. Here the Cell-theory seems, at first sight, 

 to fail ; but we are soon taught otherwise, when we examine 

 the generation of the fibres as exhibited in the incompletely 

 formed portion of the cortical substance of a feather, which 

 is in progress of formation within the capsule. The cortex 

 is then seen to consist of large flat epithelium-cells, each 

 having a beautiful nucleus, with one or sometimes two 

 nucleoli. Some of these epithelial tables are long flat stripes, 

 others are of an irregular rhomboidal form. They- are very 

 firmly connected together. Each cell generates several fibres, 

 and the transitions may be readily observed at different 

 parts of the same preparation. Plate II, fig. 13, represents 

 them. The cells at first are flat tables, having a smooth 

 margin, a slightly granulous aspect, and containing a very dis- 

 tinct nucleus (fig. 13, a). Upon their margins and sur- 

 faces indistinct fibres gradually become visible, which project 

 out insulated from the edges, but are connected together upon 

 the surface by the substance of the tables (fig. 13, b). At 

 this stage the fibres are pale, and the nucleus of the cell still 

 quite visible. The fibres afterwards become more sharply and 

 darkly defined; the insulated portions projecting from the 

 edges are larger, the part of the table connecting them together 

 becomes more indistinct, and the nucleus begins to wane 

 although it is still distinctly perceptible, and the nucleolus 

 especially so (fig. 13, c). At length all traces of the original 

 cell and the nucleus disappear, and we see only dark, stiff, 

 thin fibres, which are closely connected together but' may 

 still be recognized as being insulated for a space, the length of 

 the original table (fig. 13, d). These fibres, therefore, also 

 originate from cells, and that not so much bv an elongation 

 ol the cells, as by their division into several fibres. As the 



