1. Korngold, L., van Leeuwen, G., and Miller, D. G., Nature, 183, 330 (1959).
2. Tomasi, T. B., J. Immunol., 86, 427 (1961). Metzgar, R. S., and Grace, jun., J. T., J. Immunol., 86, 578 (1961).
3. Peetoom, F., Rose, N., Ruddy, S., Micheli, A., and Grabar, P., Ann. Inst. Pasteur, 98, 252 (1960).
4. Pearse, A. G. E., Histochemistry, Theoretical and Applied (Churchill, London, 1960).
5. Armstrong, J. A., Exp. Cell Res., 11, 640 (1957).