In Reply.—
Crounse and Bentley-Phillips suggest the existence of a previously undescribed hair-shaft disorder characterized by fragile or easily compressible hairs. Crounse has noted that the pressure necessary to produce the artifact of pseudomonilethrix is variable, and wonders if this is related to some shaft abnormalities. I have found that the pressure necessary to cause an indentation in normal hair is variable. I tested the hairs from five subjects without hair-shaft abnormalities and with variable cosmetic use histories (including my own presumably normal hair). Two or more hairs from each subject were overlapped, and a similar amount of finger pressure was exerted between the two glass slides in each test. No pressure measurement was done. The results suggest that the ability to produce the artifact is related to two conditions. The first condition is the diameter of the hair. It requires more pressure on the slide to induce the artifact