Abstract
Some evidence which indicates that the role of chemical sensitization is different for exposures to low and to high intensities have been demonstrated with a model emulsion. This paper presents a review of several published reports and offers some new information. The author concludes that the sensitivity specks on the surface of the grains are responsible for sensitivity at high intensities, whereas the silver-ion gelatin complexes and a small group of silver-atoms surrounded by gelatin attached to the grain surface are responsible for sensitivity at low intensities.