Differential Staining Of Cobalt‐ And Nickel‐Filled Neurones Using Rubeanic Acid

Abstract

A staining procedure is described which differentiates with distinct colours, cobalt and nickel ions introduced into neurones. Densely coloured precipitates are produced with these ions when rubeanic acid, a spot‐test reagent, is added. Formation of the coloured complexes takes place within a few minutes, and may be followed under the dissecting microscope. This technique permits observation of the relative positions, within ganglia, of somata related to two emergent nerves following multiple axonal‐backfilling. It also appears to be of value in tracing neurone branching after the intracellular injection of ions.