LT WoegeeREEeT PRES > avage” ERE SPIOIe, VAT iT EME EOSSOONER ete a : Mes ' aMia, BAP CATsaTé rea gE CPUS RATaRA AS AECD-3446(App. ) pare 9b)« It would seem that the tumors are formed because the processes of cell ation and intercalary growth which would normally cause a stem to increase th are somehow stopped. It is interesting to note in this connection e growing points in the tumor tissue develop in a phyllotactio sequence re 10) A recent paper on radiation injury in barley from absorbed PS2 is of Efoular interest here (24). It was found that when a meristematic region as that of the root or stem tip was subjected to a constant, relatively KHlevel of radiation from absorbed P32, cell division ceased and the cells arged and took on an abnormally mature appearance. _ Smith and Kersten (28) working with seedlings of Vicia faba grown from radiated dry seeds found that there was little elongation in the root and BiMARSAscmty iat meristematic tissue such as cambium and pericycle actually degenerated. In their study of ionizing radiations on the broad bean root, Gray and AR oles (13) found that after high dosages of x-irradiation (three-quarters meen lethal dose of x-rays) there was a slowing down of both mitosis and out one-fourth normale Wan interkinesis in the meristematic region so that the rate of elongation was only However, in the proximal half of the meristematic lls were not formed in the distal half to maintain the constant total number ed been injured. In another article (19), she also states that a constant AEB, Beatle 27 his development of the laterals would indicate that the terminal meristem 2 + jombined with continued differentiation." ar The effect was "in the main one of mitotio inhibition. - eo BOA LIEN TE beNCO eegaaraset eee gyre ymfe of meristematic cells. aONON dka BO ‘égion cells continued to differentiate at roughly the normal rate but fresh