In an effort to detect a pattern, the five regions of Table 1 pertaining to slope were assigned the following approximate time-spans in days, respectively: <100, 100-300, 300-700, 700-1200, and 1200-2300. Because the points of inflection of the various curves do not coincide, these limits for the five periods had to be arbitrary. Omitting the first eight curves, and, therefore, considering only the post-Mike material (curves 9-104 inclusive), the slope for a curve was entered in the blank Space so that a slope was available for each of the five time-periods involved. Computation of mean and standard deviation (VSx2/(n-1)), not standard error, of the 92-96 slopes for each of the five time-periods gave, respectively, these results: -1.35f0.45; -1. 260.28; -1. 2510. 34; -1,25t0.37, -1.780.79. The mean slope of -1.35 for the period up to 100 days is steeper than for the three following periods, -1,26, -1. 25, and -1.25, but is less steep than for the last period -1.78. Likewise, the standard deviation of slopes was greater for the first than for the succeeding three periods, but less than for the fifth, and this same vari- ability is also discernible from the graphs. There is thus evidence of a general increase in rate of decay of post-Mike samples during the last three years, over the first three years, with the exception of certain samples to be discussed later. The present decay rates may be compared to the theoretical gross beta decay curve for slow-neutron-induced fission products