Abstract In a preceding issue of this journal 2 the the writer pointed out that it had been possible to ascertain which hens were the best layers in a small group of White Plymouth Rocks, (maintained as an experimental flock at the Rhode Island Agricultural Experiment Station) by resort to a method which involved the weighing of the April or the September eggs, and by then calculating, for each individual of the flock, the relation which the mean weight of these April or September eggs bore to the mean weight of the first ten eggs laid by the same bird at the outset of her first laying year. It was pointed out that those hens which showed the highest percentage of increase in mean weight of eggs when this weight was measured at the period of the vernal or of the autumnal production maximum, were, on the average, the best producers of …