he Station 5 is located 160 miles southwest of Fnivetok and station 55, 90 miles due north of Eniwetok (Fig. 1). Plankton from stations 5 and 55 yielded similar radiochemical analytical results and in eddition have almost identical gamma spectra, which are essentially the same as thet of the plankton samples from one of the neighboring stations, 54 (Fig. 11). Station 42 wss taken 470 miles west of Eniwetok. The iso- topic content of plankton from this station was clearly differ- ent from that of stations 5, 54 and 55 on the bases of both chemical and ganma spectrum analysis. Compartsons of the relative activity of the different tsotopes from plankton at stations 5, 55 and 42 as determined by chemical analysis with the expected activity based on the Hunter and Ballotlcurves are as follows: Isotope gp99 90 cs? Bal37.140 Expected percent * Observed percent at stations 5S and 7.5 0 él. él. 0 <1. 55 ha 1.5 0 41. colt pptt4 16. 8.2 Triv. R.E. 15. 4.5 5.1 3.0 3.0 Rut? Rut _pptO zr’? 5.90 12.5 Coo! 298,60 Q an°? 0 28. 3.0 ol tt 20. el. 31. 6.0 * Based on an average 8-month interval following detonation. + According to the gamma spectrum, Zn 65 saacounts for approxi- mately 50 percent of the total activity at stations 5 and 55.