By application of the “centroid” method of Barton, David and Merrington to a number of H3-thymidine radioautographs, it was determined that the human late-replicatingX chromosome lies towards the periphery of the metaphase in a significant number of cases. Further, in agreement with earlier findings by other authors, the centromeres of chromosomes 1, 2 and 3 were found to lie closer together than is to be expected on a random hypothesis.
