In the night preceding the day last mentioned the hair of the head and beard of the patient, formerly blond, became gray.

Accurate examination by Landois showed the pigment contents of the hair to be unchanged, and led him to believe that the white color was solely due to the excessive development of air-bubbles in the hair shaft.

Popular belief brings the premature and especially the sudden whitening into connection with depressing mental emotions.

We might quote the German expression--"Sich graue Haare etwas wachsen lassen" ("To worry one's self gray").

Brown-Sequard observed on several occasions in his own dark beard hairs which had turned white in a night and which he epileptoid.