The differentially pumped electron microscope hydration chambers developed in this laboratory under the project award GM 16454 are to be used in two areas: (1) electron diffraction of wet cell membranes (Dr. S. W. Hui) and (2) electron microscopy of whole wet, unfixed and unstained cells (Dr. N. C. Lyon). Published work in both of these areas will be extended in the next 3 years in order to define the full extent to which this new type of electron microscopy yields new information about membranes and cells. Conventional (100 KV) fixed beam electron microscopy, scanning transmission microscopy (40 to 100 KV) and fixed beam and scanning high voltage electron microscopy (up to 1.2 Mev) will all be used in conjunction with present environmental chambers. Existing specially designed Faraday cages will be used to determine the electron exposure and radiation damage to all specimens. Particular attempts will be made to record some types of cell movement in the E. M. environmental chamber.