1. Bergman, F.: To be published.
2. Brunk, U., and O. Sköld: The oxidation problem of the sulfide-silver method. Acta path. microbiol. scand. (in press) (1967).
3. Bryan, J. H. D., and B. R. Brinkley: A silver-aldehyde reaction for studies of chromosome ultrastructure. Quart. J. micr. Sci. 105, 367?374 (1964).
4. Falkmer, S.: Unpublished results.
5. ? B. Hellman, and G. E. Voigt: On the agranular cells in the pancreatic islet tissue of the marine teleost, Cottus scorpius. Acta path. microbiol. scand. 60, 47?54 (1964a).