The method described was found especially valuable for the study of synaptic connections and unimpregnated cells. Brains and spinal cords of the young cat, dog and frog were fixed by perfusion with gum acacia saline and formalin. The brains and spinal cords were removed and immersed in 10% formalin in saline for two weeks or more. Tissues were sliced into blocks 3 mm thick, washed and impregnated in a modified Golgi-Cox solution for from 6 to 8 weeks. Parlodion sections of 80 μ to 100 μ thick were treated with 5% ammonium tetroxide and counterstained with 0.25% cresyl fast violet. The sections were then differentiated in 95% alcohol, dehydrated, cleared and mounted. The method tends to prevent shrinkage, promote staining of axons, terminals and synapses and stains unimpregnated neurons.