Topinard remarked that it is easy to confuse the fineness of hair with softness and the coarseness with harshness, and indeed well-cared-for straight or wavy hair often appears fine while crisp Negro hair appears coarse.Because of the marked differences in the size of hair from various racial groups some workers have attempted to give a numerical value to this by measurement of hair shaft diameters. Pruner-Bey, Latteux, Frederic and others have given tables showing the variation in certain races. Bernstein and Robertson in 1927 were the first to attempt to separate races by the weight of a given length although the technique as a type of hair study was suggested by Friedenthal in 1912. The results obtained by Bernstein and Robertson apparently have justified subsequent investigators in including weight among the other characteristics of racial hair samples. It would be simple indeed if the fineness or coarseness of the hair could be reduced to some convenient mathematical expression such as the weight of a given length. However, before we can assume valid conclusions from these findings, certain factors intimately related to hair weight must be considered. As Bernstein and Robertson pointed out and Trotter later verified by statistical correlations, the one most important factor in differences of weight is the size of the hair shaft. Bernstein and Robertson also believed that variations in the amount of pigment and air influenced the weight, that these were related to race, and that therefore the weight 'Part I1 of a study of human hair under the direction of Dr. Fay-Cooper Cole, department of anthropology, The University of Chicago.