1391 
Leistung einsetzt und dann mit mancherlei Schwankungen allmahlig 
abnimmt, bei einer zweiten Gruppe von Menschen erreicht die Arbeit 
erst nach längerer zeit ihr Maximum, um dann allmablig abzunehmen, 
bei einer dritten tritt das Arbeitsmaximum erst gegen das Ende 
einer längeren zeit ein.” As not a single group of boys or girls 
worked quickest in the first period, we could not verify experi- 
mentally the occurrence of the first type. To the second type belong 
no doubt the fairly-quick children with the greatest working-rate in 
the second period, which ends more slowly with the boys than the 
girls, but begins stronger with the latter than with the former. No 
more can it be doubted but that Mrumann’s third type is represented 
by the quick workers among the boys and the girls, that work 
hardest in the third period and equally hard in the first and the 
third, just as by the slow girls, that work quicker and quicker and 
by the slow boys who, in spite of a fair start, begin to slacken a 
little in the second period, but nevertheless attain their maximum 
in tbe third. 
5. After the 8 year the working-type is developed to maintain 
itself at the very least till the 12? year. New inquiries with older 
children will have to be made to ascertain whether or no, and if 
so when, changes will occur still later. 
6. The general rule that accuracy decreases with the working-rate 
does not only hold good for the working-time and the total number 
of mistakes, but also for the groups of the first, the second and the 
third period into which we have split them up. 
90 
Proceedings Royal Acad. Amsterdam. Vol. XXIII. 
