explanations for in others or for It has also been fragmentary data the success of 1311 therapy in some patients and the failure the overly destructive effect on the tHyroids in st Hil others. hoped that such models might be used to "plug in" from less completely studied patients and thus esti te the blanks in the kinetics of other patients. Yur need for mathematical ssistance in the national study hes been longstanding. The demamis on the per nnel fer e@ Turnmeve: analysis of other data in the national study have been so heavy and of personnel so frequent that little mre thw a superficial review ula be done with the studies on kinetics. Although this naticnal study is veaiins ad many interesting features on the comparative results of £227therapy thyroidectomy, it is apparent from the superficial review that the | are so fragmentary on most of the patients in that retrospective study estimate of the individual doses of radiation to the glards will be On the other hand, the data from or leberat ory, based cn the above grea observations and collected in a prospective imunner under inhis contrad ay tc be useful. These data are now in tne hands of Dr. A. Bertrand Brill of Vandertilt University for analysis by the methods of Eerman. During the past year, Dr. Brill has carried out scm analyses or the data He feels quite encouraged about paining mear ingsul which we furnished hin. interpretations on the kinetics, using modifications of the models d@vised by Berman(which were devised for study of normal iodine kinetics with «7 acers rather than therapeutic doses). Dr. Brill is particularly interested in ay cases on which we have serial quantitative determinations of changing iodinatd d compounss in the bleed following treatment. Dr. Brill has submitted an epplics ticn fora grant to support work with these data. It is hoped that the support Wil? be available. He was instrumental in the initiation of the national stu dy end has remained deeply interested in the problem. t will lead to mre precise application of tt Any informationirk therapeutic dose of 1517 and the avoidarce of long latent hypothyrois important. The observations being made currently cn selected petien hyperthyroidism are not experimental in nature, but merely prolenged detail so that the outcome of therapy for that patient is understood F and is of value if the individual requires more than one cose of 131 therapy is too destructive. A STUDY OF NEOPLASAS AS THEY DEVELOP IN IRRADIATED THYRCID We have been concerned with, and publisned observeticns on, the nuclear forms occasionally encountered in human thyroics which had p been treated with 1317. We have also been concerned with the occasi which develcps in rat thyroids that had been given smal? doses oF 13 subsequently stumulated with antithyroid erugs. In the same rat nuclear fcrms are seen. The method of using tritiated thymidine to identify by auteradi nuclei that are undergoing mitosis has been used in our laboratery f years. We have been using this labeling technique to atterpt te ic of neoplasms as small aggreraticns of cells in irradiated rat thyroi based on the assumption that any cluster cf cells destined to be an display a different rate of incorporaticn of tritiated thymidine in will cells of the surrounding tissue. pity those quite sce ify the aset mciei than