8 EVENINGS AT THE MICROSCOPE. 



worsted, vary in diameter from aoVo^^^ to y^o^^^ ^f an 

 inch ; and there are, upon an average, about two im- 

 brications in a space equal to the diameter. Xo colour 

 is i^erceptible in tliese specimens ; thej are as 

 transparent and colourless as glass. The im- 

 bricated plates project here considerably more 

 than in either of the examples we before exam- 

 ined ; the " teethj" liowever, form an obtuse 

 angle. 



We shall presently see the importance of this 

 imbricate structure; but we will first look at a 

 fcAV more examples, in which we shall find it 

 still more strongly developed, in conjunction 

 with some other peculiarities. All the hairs 

 that we have looked at are what I have called 

 fibrous in their interior texture, but those of 

 many animals are more distinctly cellular. 



Thus, in these specimens, plucked from the 

 BiiEEp-sw'Lfur of the Cat that lies coiled up on the hearth- 

 rug, we see, first, that the imbrications are short, being 

 about equal to the diameter in length, but ai'e very 

 strongly marked ; though, like those of the Sheep's 

 wool, obtuse. Hence, the contour is extremely like 

 that of the stipe of an old rough palm-tree. There is 

 a distinct bark {cortex), which is thick, and marked with 

 longitudinal lines, which add to the resemblance just al- 

 luded to. The interior is clear, marked off at pretty 

 regular intervals by the broad flattened medullary cells, 

 in single series, each cell occupying, for the most part, 

 the whole breadth of the interior. These cells are trans- 

 parent and apparently empty; but their walls appear 

 opaque and almost black, — an optical illusion, dejDen- 

 dent on the absorption of the light by their surfaces at 



