1. Geren, B. B., Exp. Cell Res., 7, 558 (1954).
2. Robertson, J. D., Progress in Biophysics, 10, 344 (Pergamon Press, 1960).
3. Finean, J. B., Proc. Roy. Soc. Med., 54, 19 (1961).
4. Lubinska, L., and Lukaszewska, I., Acta Biologiae Experimentalis, 17, 115 (1956).
5. Webster, H. de F., and Spiro, D., J. Neuropath. and Exp. Neurol., 19, 42 (1960).