Studies are also being conducted by Pollard and associates at Pennsylvania State University in an attempt to formulate a theoretical basis for the description of the processes of synthesis, growth, division, and differentiation of the living cell. Such a theory would be basic to an understanding of very primitive life forms or prebiological material which might be found elsewhere in the universe. For these purposes, studies are being undertaken in macromolecular reproduction which differ from the studies involving cellular genetic material. Theories concerning the problem of replication of cellular structures and information storage in two-dimensional systems are being developed. Theories are also being developed about the mechanisms which control and regulate receptor and enzymatic activities within the cell. One study involved the rate of mutation in cells and disposed of the suggestion that the process of mutation consists of a "tunneling" of proton from one base to another in DNA. Such a suggestion can no longer be advanced as a major explanation of mutations. Work is also being conducted on the centrifugation of cells of _E. coli_. It has been shown that cells exposed to as little as 100 g have a modification in their function. This has been looked at from the point of view of thymine uptake, which would be concerned with the formation of DNA, and also from the point of view of the induction of an enzyme, which would correspond to the transcription of the DNA. Preliminary experiments in the latter case indicate considerable centrifugation effect. The thymine uptake is affected, but not nearly as much as formerly thought. Further work is in progress in this area. Important work has been completed on the cells of _E. coli_ grown on maltose, which can be induced to produce betagalactosidase by the addition of thiomethyl galactoside. If cells are irradiated shortly after induction, the transcription of the DNA ceases and the enzyme produced by the messenger RNA is observed to reach a maximum. This enables the calculation of the half-life of unstable messenger RNA. The half-life for this decay is readily measurable, and values are given over a temperature range of 17° C (5.2 minimum) to 45° C (0.56 minimum). These agree very well with half-lives measured by others by inducing for short times and measuring the course of enzyme formation. The rate of transcription is involved in the kinetics of cessation of enzyme induction, and the rate of transcription can be measured. Arrhenius plots for this rate and the rate of decay are given, and the activation energies measured are about 16 000 cal/mole. The cessation of transcription is linked to the degradation, possibly of only one strand, of DNA.