These experiments were made on 238 boys and 224 girls, between the ages of 9 and 14, in the schools at Kiel. Eight different kinds of memory were investigated, involving in each group a test of the ability to remember in exact order nine sensory impressions (nine objects exhibited in succession, nine figures repeated, nine names of visual objects repeated, nine names of states of feeling, nine difficult unknown words, etc.). Among the boys the average order of excellence reached was as follows (in decreasing values): real things, figures, words referring to touch, visual words, words representing sounds, actual sounds, words referring to feelings, difficult words. In every group (except that of objects exhibited) there was a regular improvement with age. In regard to objects seen, sounds heard, and representations of feeling, there was a marked improvement in memory about the thirteenth year. The memory for figures, and for sound-words, touch-words, and feeling-words, showed most rapid development at an earlier age (ten to eleven years). There was no tendency to a simultaneous development in all the groups; mental energy seemed to be concentrated on one group at a time.