Pollard has suggested that one important action of ionizing radiation is concerned with the transcription of the genetic message into RNA. Clayton and Adler ([ref.159]) showed that induced catalase synthesis in _Rhodopseudomonas spheroides_ is inhibited by low doses of X-rays, giving experimental support to the idea. Pollard and Vogler ([ref.160]), using cells in which the process of induction involved permease, showed that there is some sensitivity to gamma radiation. Novelli et al. ([ref.161]) found a reduced sensitivity as compared with colony formation, but it is still a considerable sensitivity. The process of induction of an enzyme indicates that the transcription of the genetic message is repressed by something which can be acted on by a small molecule, the inducer, to remove repression and permit the formation of messenger RNA, which then acts to make the enzyme. The messenger RNA undergoes decay through a process which is still not clear. Very elegant measurements by Kepes ([ref.162]) show that for the messenger RNA for betagalactosidase, the half-life is 1.02 min at 37° C and 2.05 min at 25° C. The time of onset of enzyme formation after induction was found to be about 3 minutes. If the process of transcription is indeed sensitive to ionizing radiation, then the irradiation of cells which have just been induced should show formation of the enzyme to the extent of formation of new messenger RNA within a few minutes, plus the formation of the enzyme while the messenger RNA is decaying. This pattern was found by Clayton and Adler. The experiments conducted by Pollard and associates amplify and extend their work and also agree with the work of Kepes ([ref.162]). BIOINSTRUMENTATION Fernandez-Moran (refs. [ref.163]-[ref.165]), at the University of Chicago, has devised a new multielectrode electrostatic lens which he has incorporated into an electron microscope. This necessitated the development of a novel high-voltage power source and voltage regulator of extreme stability and accuracy. Some promising work has now been done on superconducting lenses. In a series of experiments with a simple electron microscope without pole pieces, using high-field superconducting niobium-zirconium solenoid lenses in an open air core, liquid helium Dewar, electron microscopic images of test specimens have been recorded while operating at 32 200 gauss in a persistent current mode, with regulated accelerating potentials of 4 to 8 kilovolts. These preliminary experiments have demonstrated the exceptional stability of the images (both short term and long term) over a period of 4 to 8 hours and the relatively high quality of the images. Progress has been made on the viscosimeter for high intrinsic viscosities. This is now working, and the viscosity of DNA preparations has been measured. It is hoped to use the viscosimeter to study the variation in DNA viscosity as a function of the cell cycle.