Materials and Methods.- Observations.- Motoneuronal Centers and Neighbor Regions.- Sensory Relay Centers and Neighbor Regions.- Specific Precerebellar Centers.- Other Well Outlined Centers.- Diffuse Reticular and Tegmental Regions.- Midline and Paramedian Nuclei of the Brain Stem.- Subependymal Regions.- Discussion.- 1. Cholinergic Transmission in the Nervous System.- 2. The Significance of a Positive AThChE Stain.- 3. The Distribution of Acetylthiocholinesterase in the Brain Stem.- Summary.- Abbreviations.- References.Springer Book Archives