130 EXCRETION. 



but there was no diminution in the quantity of pigmentary 

 matter. The possibility of sudden blanching of the hair is 

 further illustrated by a curious observation lately made by 

 Dr. Brown-Sequard. This physiologist observed in his own 

 person four white hairs upon the cheeks upon one side, and 

 seven upon the other, mixed with the dark hairs of the beard. 

 These he pulled out, and two days after, he found two hairs 

 upon one side, and three upon the other, that were white 

 throughout their entire length. This observation he veri- 

 fied several times, and from this he concludes that there is 

 no doubt of the " possibility of a very rapid transformation 

 (probably in less than one night) of black hairs into white." 



The microscopical examinations by Dr. Landois and others 

 leave no doubt as to the cause of the white color of the hair 

 in cases of sudden blanching ; and the instances we have 

 just quoted show that the fact of the occurrence of this phe- 

 nomenon can no longer be called in question. All are 

 agreed that there is no diminution in the pigment, but that 

 the greater part of the medulla becomes filled with air, small 

 globules being also found in the cortical substance. The 

 hair in these cases presents a marked contrast with hair 

 that has become gray gradually from old age, when there is 

 always a loss of pigment in the cortex and medulla. How 

 the air finds its way into the hair in sudden blanching it 

 is difficult to imagine ; and the views that have been ex- 

 pressed on this subject by different authors are entirely theo- 

 retical. 



The fact that the hair may become white or gray in the 

 course of a few hours renders it probable that many of the 

 cases reported upon unscientific authority actually occurred ; 

 and these have all been supposed to be connected with in- 

 tense grief or terror. The terror was very marked in the 

 case reported by Dr. Landois. In the great majority of 



1 BROWN-SEQUARD, Experiences demontrant que les poik peuvent passer rapide- 

 ment de noir au blanc, cJiez Vliomme. Archives de physiologic, Paris, 1869, tome 

 ii., p. 442. 



