[Structure of the neuropile of the abdominal brain of polychaetes]

By means of vital staining of neuronal elements with methylene blue, new data were obtained on the structure of neuropil in the abdominal brain of Polychaete (Nereis diversicolar). Neuronal composition and interrelationship between sensory, motor and associative areas are clarified. Dorsoventral differentiation of the neuropil is analyzed; common level of intraneural relations of Polychaetes in the line of Annelida is determined.