1. Cheema, A., Henson, J. B., and Gorham, J. R., Amer. J. Pathol., 66, 543 (1972).
2. Porter, D. D., Larsen, A. E., and Porter, H. C., J. Immunol., 109, 1 (1972).
3. Cho, H. J., and Ingram, D. G., Canad. J. Comp. Med., 37 (in the press).
4. Eklund, C. M., Hadlow, W. J., Kennedy, R. C., Boyle, C. C., and Jackson, T. A., J. Infect. Dis., 118, 510 (1968).
5. Porter, D. D., Larsen, A. E., and Porter, H. C., J. Exp. Med., 130, 575 (1969).