Abstract
Rhode Island Red embryos, destined to develop into adults of comparatively large size, proliferate cells at a faster rate than White Leghorn embryos, destined to develop into adults of comparatively small size. 1 It is known that glutathione (sulphydryl) stimulates cell proliferation, and that rapidly growing rats and rabbits have a greater concentration of glutathione in their body tissues than less rapidly growing controls. 2 - 3 Furthermore, fasted new-born rabbits which are destined to develop into large adults have a greater concentration of glutathione than those destined to develop into small adults. 4
The following experiment was performed in order to determine the glutathione concentration of White Leghorn and Barred Plymouth Rock embryos, and to ascertain whether or not a difference in concentration exists between the two breeds. Most of the Leghorns, and all of the Barred Plymouth Rocks used in the experiment were descendants of the stocks used by Asmundson and Lerner in studies on the inheritance of adult body size. It was definitely known that the Rocks had a significantly greater post-hatching growth rate than the Leghorns. 5
The range of adult weights of the Leghorn hens used for the production of eggs in the first experiment was from 1418 to 2250 gm., with a mean weight of 1814, and of the Barred Plymouth Rocks, 2481 to 3143 gm., with a mean weight of 2881. There was a considerable variation in the weight of the Leghorn sires, the range extending from 1940 to 2915 gm. with a mean of 2385. The only Rock male used weighed 3669 gm.
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