1. For example, Dalgaard, J. B., Nature, 162, 811 (1948). Shugar, D., Szenberg, A., and Sierakowska, H., Exp. Cell. Res., 13, 424 (1957). Pearse, A. G. E., Biochem. J., 68, 17 P (1958).
2. Barnard, E. A., in “New Approaches in Cell Biology”, edit. by Walker, 145 (Acad. Press, New York, 1960).
3. Barnard, E. A., in “General Cytochemical Methods”, edit. by Danielli, 2 (Acad. Press, New York) (in the press).
4. Pelc, S. R., Internat. J. App. Rad. Isotopes, 1, 172 (1956).
5. Fitzgerald, P. J., Eidinoff, M. L., Knoll, J. E., and Simmel, E. B., Science, 114, 494 (1951).