80 THE HAIR. 



coloured hair, that the iron which is present, and to which 

 Vauquelin had drawn attention, exerts no influence whatever 

 on its colour." (LEHMANN.) 



The medulla or pith before mentioned is in some thin hairs 

 entirely absent, or the spherical cells are scanty, and pressed 

 into various shapes. 



Mr Wilson says, " Although the central part of the hair of 

 man is a loose pith, in which the original spherical form 

 of the cells is more or less completely lost, yet in many 

 animals this form is retained with the most exact precision, 

 and such hairs appear to contain in their axes a very beauti- 

 ful string of beads, rendered strikingly obvious, in dried 

 hairs, by the emptiness of the cells. Such is the appearance 

 of the very fine hairs of the hare or mouse. In thicker hairs 

 from the same animals, there are two or three or more rows 

 of cells, and the largest hairs, from the number of these rows, 

 bear a resemblance in structure to an ear of maize. This is 

 the chief modification which the pith of the hair undergoes 

 in the animal kingdom, being more completely or less cellu- 

 lated, and holding a greater or less proportion to the entire 

 bulk of the hair ; sometimes, indeed, as in some hair in my 

 possession, from one of the deer tribe, the whole texture of 

 the hair is cellular, the other two portions being condensed 

 into a thin envelope. In the feather of a bird, which is a 

 modification of hair, the white pith with its dense external 

 covering is very evident in the shaft, while the quill is an 

 illustration of the outer parts alone, the transparent puckered 

 membrane, which is drawn out of the quill when first cut, 

 being a single row of dried-up cells. In the growing feather, 

 the contents of the quill would be found distinctly cellulated. 



"The fibrous portion of hair is the source of its strength, 

 and the degree of strength possessed by these delicate threads 

 is almost beyond belief. 'A single hair from a boy eight 



