LIST OF DIAGRAMS.FIGUREPAGE1.[Origin of instinct by organic selection][35]2.[Reflex and voluntary circuits][107]3.[Outer surface of the left hemisphere of the brain][110]4.[Inner surface or the right hemisphere of the brain][111]5.[The speech zone (after Collins)][113]6.[Mouth-key][131]7.[Apparatus for optical experiment][135]8.[Memory curves][140]