1390 
The fairly-quick workers of either sex make the largest number 
of mistakes in the second period — with the exception of the boys 
of 12 and the girls of 11. Fewest mistakes were ever made in the 
first period (one exception: the girls of 9). Here again the difference 
in the percentage of the mistakes in the third and the second period 
is very small, so that we find also for the fairly-quick workers that 
the general rule (the number of mistakes increases with the working- 
rate) not only holds for the working-time and the total number of 
mistakes, but also for the groups into which we have split them 
up. The slow workers among the boys and girls form an exception 
to this almost general rule. Although they work hardest in the third 
period, it is only the boys of 8 and 10, and the girls of 8, 9, and 
10 that make most mistakes in this period. The boys of 9 and 11 
and the girls of 11 and 12, on the contrary, make most mistakes in 
the second period. And whereas the difference in the percentage of 
mistakes is mostly small for the second and third period in the 
exceptional cases of the other categories, it is here rather consider- 
able except for the girls of 12. 
The reasons for this deviation among the slow workers we were 
not able to detect. Finally it is worth recording that also the slow 
workers make fewest mistakes in the first period. Boys of 11 years 
form the only exception in the 9 cases of slow workers. 
CONCLUSIONS. 
1. As regards the quick workers among the boys and girls more 
work is done in the last period than in the first and the second; 
in the latter two the rate is equal. With years this difference in 
the working-rate, which occurs in this category of boys between the 
third and the first period, first decreases (from 8 to 10); then it 
remains constant. For the quick workers among the girls this differ- 
ence increases a little, though not much. from 10—12. 
2. The fairly-quick boys always work hardest in the second 
period and in the third harder than in the first. The fairly-quick 
girls also work hardest in the second period, but in the first harder 
than in the third. 
3. The slow boys and girls work quickest in the third period, 
with the exception of a few. But whereas the boys work quicker 
in the first than in the second, just the reverse is the case with 
the girls. 
4. We agree with Mrumann in distinguishing three principal forms: 
“Indem bei einigen Individuen die Arbeit mit einer relativ grossen 
