128 EXCRETION. 



physiologists are of the opinion that the hair may become 

 almost white in the course of a few hours, and this, indeed, 

 is a popular impression ; but others assume that such sudden 

 changes never take place, although it is certain that the hair 

 frequently turns gray in a few weeks. In examining the 

 literature of this subject, it is difficult to find in the older 

 works well-authenticated cases of these sudden changes, and 

 most of those that have been quoted are taken upon the 

 loose authority of persons evidently not in the habit of mak- 

 ing scientific observations. Such instances, unsupported by 

 analogous cases of a reliable character, must necessarily be 

 rejected, as not fulfilling the rigid requirements demanded 

 in scientific inquiries, in which all possible sources of error 

 should be carefully excluded. It is not necessary, therefore, 

 to quote the instances of sudden blanching of the hair re- 

 corded by the ancient writers, nor those well-known cases 

 of later date, so often detailed in scientific works, such as 

 that of Marie Antoinette or Sir Thomas More ; and it 

 seems proper to exclude, also, cases in which the blanching 

 of the hair has been observed only by friends or relatives ; 

 for in most of them the statements with regard to time are 

 conflicting and unsatisfactory. 



Regarding the subject, however, from a purely scientific 

 point of view, there are a few instances of late date, in which 

 sudden blanching of the hair has been observed, and the 

 causes of this remarkable phenomenon fully investigated by 

 competent observers ; and it is almost unnecessary to say 

 that a single well-authenticated case of this kind demonstrates 

 the possibility of its occurrence, and is interesting in connec- 

 tion with the reported instances which have not been sub- 

 jected to proper investigation. One of these cases is report- 

 ed in Virchow^s Archiv, for April, 1866, by Dr. Landois, as 

 occurring under the observation of himself and Dr. Lohmer. 1 

 In this case the blanching of the hair occurred in a hospital 



1 LANDOIS, Das plotzlicfie Engrauen der Haupihaare. VIRCHOW'S Archiv, 

 Berlin, 1866, Bd. xxxv., S. 375. 



