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snails in the 80000 r and 40000r groups, half of the snails in the
20000 r group and 5 of the controls had died, but none died in the
Mortality rates in other groups were similar to
10000 r croup.
the controls.
By the end of the month 7 controls had died and
mortalities in other groups were:
20000 r, 53; 10000 r, 0;
SOOO. r, 13 2500 r, 13; 1000 r, 0; and 500 r, 4.
The relatively high
mortality in the 500 r group may possibly be attributed to rough
handling, as they were the first ones irradiated.
Project X.
Bikini Resurvey of 1948.
In the counting and sample preparation laboratory, periodical counts
were continued of the selected Bikini and Eniwetok plates for
determining rate of decay of the activity.
‘The preparation of ashed
samples of Bikini and Sniwetok materials for U.C.L.A. was continued,
The technique of preparing coral samples for counting was chanred.
The present procedure is to pulverize the sample with a mortar and
pastis, place about one-half a gram of sample on a plate and cover
with 0.5% solution of Formvare in ethylene dicloride to make sample
adhere to plate.
Results are sood.
For the purpose of separating
those samples of low activity from those of background only, a recount
Was started of the Bikini fish samples that on first count were only
4 counts or less higher than backsround.
A cheek on the ashing
technique used up to the present time indicates that considerable
activity may have been driven off during the process.
Samples in
which acid was not used in preparation gave substantially higher
counts than those prepared by the original method.
investigated further.
This is to be