When a series of digits was immediately repeated orally and a record made, it was found[23] that while from the age of eight to twelve the memory span increased only eight points, from fourteen to eighteen it increased thirteen points. The number of correct reproductions of numbers of seven places increased during the teens, although this class of children remain about one digit behind normal children of corresponding age. In general, though not without exceptions, it was found that intelligence grew with memory span, although the former is far more inferior to that of the normal child than the latter, and also that weakness of this kind of memory is not an especially prominent factor of weak-mindedness. Shaw[24] tested memory in 700 school children by dividing a story of 324 words into 152 phrases, having it read and immediately reproduced by them, and selecting alternate grades from the third grammar to the end of the high school, with a few college students. The maximum power of this kind of memory was attained by boys in the high school period. Girls remembered forty-three per cent in the seventh grade, and in the high school forty-seven per cent. The increase by two-year periods was most rapid between the third and fifth grades. Four terms were remembered on the average by at least ninety per cent of the pupils, 41 by fifty per cent, and 130 by ten per cent. The story written out in the terms remembered by each percentage from ten to ninety affords a most interesting picture of the growth of memory, and even its errors of omission, insertion, substitution and displacement. "The growth of memory is more rapid in the case of girls than boys, and the figures suggest a coincidence with the general law, that the rapid development incident to puberty occurs earlier in girls than in boys." In a careful study of children's memory, Kemsies[25] concludes that the quality of memory improves with age more rapidly than the quantity. W.G. Monroe tested 275 boys and 293 girls, well distributed, from seven to seventeen years of age, and found a marked rise for both visual and auditory memory at fifteen for both sexes. For both sexes, also, auditory memory was best at sixteen and visual at fifteen. When accuracy in remembering the length of tone was used as a test, it was found there was loss from six to seven and gain from seven to eight for both sexes. From eight to nine girls lost rapidly for one and gained rapidly for the following year, while boys were nearly stationary till ten, after which both sexes gained to their maximum at fourteen years of age and declined for the two subsequent years, both gaining power from sixteen to seventeen, but neither attaining the accuracy they had at fourteen.[26] [Illustration: Girls and Boys at Memory Reproductions compared.]