mma 10 AECD-3446 (App. ) effect of x-rays on seeds and seedlings of Helianthus annuus is the prod, of fasciation in stems, leaves and flowers. At Brookhaven National Laboratory it is reported (3) that planta = to chronic irradiation in the “gamma field" are often severely stunted a: Others show growth abnormalities such as the supernumerary buds in Trade While it ia well known that plants vary in their response to red we have found no previous record of radiation induced tumors such as tim: . described in this papers However, as has been pointed out, a similar pk has been reported, 1o@e, @ retarding of meristematic growth with contiz ferentiation; in the present oase the phenomenon was carried to such a & that large tumors resulted. The tumorous plants were limited on the tess to areas adjacent to the crater site where radioactivity was comparative A careful examination of stands of this species on several islands in es four atolls revealed no other cases of tumorous Ipomoea plants. At the time the plants were collected a radiation survey of the = site was made by Seymour and Kellogg (30). At this time the survey mezet : ot nein Rtg, corded 50,000 to 100,000 c/min. at the surface of the soil within the sr* question. A conservative estimation of the dosage received by the plas then be somewhere between 0.1 and 10 rep/week* during August of 1949, months after the actual bomb tests. Records of earlier levels of radica# and of the time when the plants first reestablished themselves are not Manet =” Sn mermnniimme: ae) = “RON “ipemne acMCPRCRAO NRE TEL yreoM N PN The tumors themselves were examined both by means of autoradiogs#® by direct tissue count for radioactivity within them, but nothing more “e traces of activity wore present in the tissue masse This is to be expo” the plant is a deep rooted one absorbing very little in the cntaminatoe™ * * Assuming Eav to be 1 meve ~ UNIVERSITY ARC ryre UNIV, OF WAsty, Lil. APITE