Firrrt indicatwns of appreciation of colour by L.-A new method of experimenting tried-Evidence of colour appreciation obtained by the method in the 21st and 22nd weeks (Table I )-The method systematically applied to L. throughout the 6tn and 7th months ( Table I I ) -T h new method improved in detail and applied to A. i n 8th and 9th months (Table III) -Discussion o f results-Comparison of the method with that of Prof. J. M. Baldwin--Summary of principd conclusions.