on sea salt which might unadvertently nave been included at the time of preservation. Tne August 1953 samples including preservative, were ev.iporated to dryness, so that the sample from Station 7 in- ciuaging 811% water accidentally used for washing: the plankton bucket, ' Nn me careful work of br. Renz: cela ay | , appeared low in radioactivity. . precess:ng the plankten samples of August 195% +s gratefully acknowledged Data after 1956 are presented as of the date of counting, rather than being corrected back to date of collecting as was done for tha 1954-55 macerial. It is probable that if corrections for decay could have been applied to the 1956 data the levels on the date of collectlon would have been fourd to be about twice as nigh as those here given for tne dite of counting, but data from later collections would have been practically unaltered. Results and discussion Tables 1 and 2 give the plankton data from 1954 to 1958, includ- ing the v.lues from which Tatle 12 of the preceding report, UWFL-43, was commtled. ia Individual plate values appear in order to show the degree of virlaollity, and for 1954-55 to permit comparison of coarse and fine mesh net samples. Fadiloacttvity is expressed per unit welght of both wet plankton and planktcnic ash in order to assess the relative. Suitir‘iity of tnese tvo buses of reporting results. . leavels of radioactivity were equilly nigh in coarsenin fine meshed nets. basis The equality prevails on either wet weight or ash weight amonz the ten pairs of simultaneous tows with coarse and fine ve (00. 5 | DO ARCHIVE S 4