Abstract
Four major categories of neurosecretory cells (A, B, C, D) were distinguished in the brain ofTriphaena pronubaL. by staining sections with paraldehyde fuchsin and counterstains. These comprised nine types of cells, seven of which were recognizable for analysis of their secretory products. Histochemical tests indicate that the lepidopteron brain has a multiplicity of neurosecretory cells, each type producing chemically different secretions.