1. J. A. Wheeler:Fields and Particles (unpublished Princeton lecture notes, 1954).
2. P. I. Fomin:Sov. J. Part. Nucl.,7, 269 (1976).
3. The space-time co-ordinates used here are of direct geometrical significance (e.g.,G. Rosen:J. Math. Phys. (N. Y.),3, 313 (1962))
4. H. Weyl:Space-Time-Matter (New York, N. Y., 1922), p. 260.
5. Tau mass value according to M. Perl: private communication (1979); alsoG. J. Feldman: inProceedings of the Nineteenth International Conference on High-Energy Physics, Tokyo, Japan,August 1978, edited byS. Homma,M. Kawaguohi andH. Miyazawa (Tokyo, 1979), p. 786.