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ABCD-3446 (App. )
effect of x-rays on seeds and seedlings of Helianthus annuus is the production
of fasciation in stems,
leaves and flowers.
At Brookhaven National Laboratory it is reported (3) that plants exposed
to chronic irradiation in the "zamma field" are often severely stunted or killed.
Others show growth abnormalities such as the supernumerary buds in Tradescantia.
While it is well known that plants vary in their response to radiation,
we have found no previous record of radiation induced tumors such as the ones
described in this papers
However, as has been pointed out, a similar phenomenon
L
?
has been reported, i.e., a retarding of meristematic growth with continued differentiation; in the present case the phenomenon was carried to such a degree
that large tumors resulted.
The tumorous plants were limited on the test islands
to areas adjacent to the crater site where radioactivity was comparatively high.
A careful examination of stands of this species on several islands in each of
four atolls revealed no other cases of tumorous Ipomoeaplants.
At the time the plants wore collected a radiation survey of the collection
site was made by Seymour and Kellogg (30).
At this time the survey meters re-
corded 50,000 to 100,000 c/fmin. at the surface of the soil within the area in
question.
A conservative estimation of the dosage received by the plants would
then be somewhere between 0.1 and 10 rep/week* during August of 1949, seventeen
months after the actual bomb tests.
Records of earlier levels of radioactivity
and of the time when the plants first reestablished themselves are not available.
The tumors themselves were examined both by means of autoradiography and
by direct tissue count for radioactivity within them, but nothing more than
traces of activity were present in the tissue masse
This is to be expected as
the plant is a deep rooted one absorbing very little in the cmtaminated surface
* Assuming Eav to be 1 meve