The Golgi Method: Its Application to the Insect Nervous System and the Phenomenon of Stochastic Impregnation

Abstract

This chapter discusses aspects of methods that impregnate single neurons in a more or less unpredictable fashion. The basic methods are discussed with respect to strategies of fixation, chromation, and metal impregnation. This is followed by discussions of a possible mechanism of impregnation based on direct observations of neurons as they are impregnated and on model substrates. It is argued that silver (or mercury) Chromate precipitates are not nucleated at a single point in the cell but usually begin to form throughout the cell. Some suggestions are also made about why cells rarely stain adjacently. Factors such as diffusion rates of silver ions into the tissue, permeability barriers, and reducing properties of chromated tissue are considered, and a model of stochastic impregnation is proposed (Appendix I).