74 PERSONAL APPEARANCES IN HEALTH AND DISEASE. 



preceding will be seen in the presence in the former of 

 dots and linear streaks of pigment which had an amber 

 colour, although of course they appear dark in the engrav- 

 ing. Lastly we have a black hair (*:), and this will be seen 

 studded with pigment granules in all parts. We learn 

 from this then that the colour of the hair depends on the 

 presence of pigment particles more or less widely dissemi- 



nated throughout its substance, whilst a purely white hair 

 is distinguished by the negative character of the absence 

 of all such pigment. That men's hairs have Been known 

 to turn " white in a single night," through sudden fear, or 

 some equally powerful emotion, is perfectly true. Several 

 well-authenticated instances are recorded. Not that the 

 pigment actually disappears from the hair ; it is probably 



* Hairs of different shades of colour. 



