“…Smaller size was responsible for the decreased dry weight of the auxin-treated embryos. Wheat is probably an auxin-satiated plant (Greenfield, 1937;Marmer, 1937), so that upon addition of auxin its growth is inhibited by the toxic action of the chemical. But the rise in the upper 1 Received for publication February 16, 1938. curve shows that the intensity of respiration, per mg. 2 Bonner (1933) reported increased respiration of of embryo weight, was greatly increased as the hor-Avena coleoptile segments resulting from the addition of an auxin extract obtained from Rhizopus suinus but mone concentration was raised from 0.01 ppm.…”