1. Wight, W., and Barua, P. K., Nature, 179, 506 (1957).
2. Roberts, E. A. H., Wight, W., and Wood, D. J., New Phytol. (in the press).
3. Kirby, K. S., Knowles, E., and White, T., J. Soc. Leather Trades Chemists, 37, 283 (1953).
4. Barua, P. K., Camellian, 7 (4), 18 (1956).