Discussion of Dr. Todd's paper. Dr. Jones. What relation have height, weight and muscular power to the radiograph? Doctor Todd. None. The dimensions are hereditary and have nothing to do with skeletal maturation. Large or small, maturation goes on just the same. Size does not count; the skeleton is scarcely affected by such things. Mr. Grant. Is there any racial variation in these measurements? Dr. Todd. Some of our children are colored, some are of the third generation of Americans, some of the second generation of Sicilians, and I have not yet found any significant difference in skeletal maturation. Dr. Gregory. Is this result not in line with your results on the study of mammals as a whole, where you found a narrow sequence in the range of the epiphyses? Dr. Todd. Yes; we have found that, with a notable exception in the wrist, there is an order in union of epiphyses which is common to mammals in general, including Man. The publication of this research is delayed pending the discovery of an effective method of graphic presentation. Dr. Davenport. Have you examined the development of bone in feeble-minded children or those of low grade? Dr. Todd. Some of our children were of low grade but not really feeble-minded; they showed no significant physical retardation. Dr. Davenport. Some of our children show retardation of one or two years in the development of ossification. Dr. Todd. I can well believe this for such a retardation exceeds but slightly the limits of retardation found in our physically backward children. Mr. Grant. Do you get the same degree of maturity in all races? Dr. Todd. Sexually, some mature several years earlier. So far as our work on Americans, Sicilians and American Negroes permits us to conclude there is no apparent racial difference in the skeletal maturation rate.