330 Dr Allen Dalzell on the Colour of Hair. 



human species, although especially remarkable in the Albino, 

 whose choroid is destitute of pigment, and hair either very 

 pale or entirely white. 



Many observers have described the granular pigment which 

 forms the first class of colouring matter, as if it was situated 

 in interspaces of the fibres. I have, however, assured myself 

 of the fact that pigment is never lodged exteriorly in the 

 cells, but always in some part of the interior, as may be 

 plainly seen in the hairs of some cervi, where the entire cells 

 are dry and empty, except of traces of colouring matter which 

 adhere to their walls. Changes, during the growth of hair, 

 often take place at regular intervals in the colour and amount 

 of these deposits. This is seen in the hairs of many of the 

 Quadrumana and Carnivora, to which classes it is, however, 

 by no means confined. 



In many hairs, the colour is uniform or diffused. Most 

 animals have hairs of this kind ; good examples may how- 

 ever be found in the short hairs from the face of the Hare, 

 in the Tapir, and yellow Bear. 



Air spaces in the shaft. — These cavities, from containing 

 air, refract light beyond the field of the microscope, and thus, 

 like the cells of the axis, give the idea of colour; these are best 

 seen in white hairs. Some authors have described them as 

 fat granules. This is inaccurate, for, on boiling with ether or 

 turpentine, they become filled with the fluid ; and even when 

 treated in a menstruum, which does not dissolve fat, they 

 lose their refractive properties, and retain only their gene- 

 ral outline. They are empty cavities situated in the cells of 

 the shaft, produced, as Kolliker supposes, by the absorption 

 of its granular pigment ; for they are not found in any hair 

 originally colourless, but only in such as have become so 

 from some cause affecting their vitality. I examined a hair 

 with one extremity entirely white, the other unaltered — the 

 former part I found filled with air cells, the latter pigment 

 cells. 



Changes in the Colour of Hair. 



The change of colour in the hair is well seen in the com- 

 mon Alpine hare, and in many of the Mustella, in which the 



