~25~- AECD -3446 FUnits of Measurement, =“ of wet tissue, the unit of measurement used in 1949 was disinte- pnns| oisper minute per gram of wet tissue, hereafter referred to asdm /8. The coaeslivitig organism... Naturally the activity per unit of wet weight is much lower i tunounof dry weight. ee. teedreting m pic/kg to d/m/g was determined from the relationshipthat one * - arte‘equals 3.7 x 10° disintegrations per second, This factor was 2.2 and has beenused in the following sections to convert the 1948 values tod/m/g. To _fantectthe 1948 values for decay, which was not done in the following sections, e xte factor is estimated to be about 1 /3, assumingthe activity is from 280-day talfstiteCe144 and its 18-minute half-life daughter pri44 which are in equilibrium. etcombined correction factor, for units of measurement and decay, would be F786 Or, 0.7. For example, if a sample were counted in September, 1948, and teedtobe 100 m pic /kg, then the count of the same sample in January, 1950, would be thout10Dd/m/g. Br ee ee: ae ~ Tt is to be remembered in making a direct comparison between 1948 and aoe tHthat the two years include unavoidable differences in localities, in ashing “srsaatng2 methods, and in some instances in species sampled. we ee = “me #0topes has not been done except for the work on cat® (see section on land i Miataby 2Dr, Orlin. Biddulph ). However, decay curves and absorption curves « UNIEDMET N Ons tad pm “UN,