Further Studies of the Terminal Oxidases in the Embryos and Young Roots of Barley

With 9 figures in the text)In a previous paper (lames, 1953), evidence was presented that was taken to show that about 80 % of the embryos' respiratory transfer of electrons to oxygen passes through the cytochrome system.The root tips of seedlings about 10 days old provided no such evidence; but gave strong indications that the function of the missing cytochrome enzyme was undertaken by ascorbic oxidase.It therefore seemed desirable to investigate the early stages of root development, and to discover whether the root tips lacked the cytochrome system from the start, or whether it failed during the first few days of growth.An investigation, using methods similar to those previously employed, was carried out with root tips during the first fortnight of their development.