1387 
to the third period. The percentages express the increase or decrease 
of working rate in the second, resp. the third period as compared 
with the preceding period. 
It now appears, that as regards the fairly-quick boys of 8 years, 
there is a large increase from I—II, on the contrary a less consider- 
able decrease from II to ILI. For the other ages the increase from 
I to II is also larger than the decrease from II to III. 
On the one side however the percentage of the increase in the 
working-rate from I-—II, and on the other the percentage of decrease 
from II to IIL remains approximately constant (resp. + 24, + 23, 
+ 22, + 22 °/, and — 15, — 16, — 15, —13°/,). The percentages 
with which the working-rate among the fairly-quick girls of differ- 
ent ages increases from I to II and decreases from II to ITL do not 
require special discussion. 
With a few exceptions the slow boys and girls (the girls from 
11—12 years) work hardest in the third period. But whereas the 
boys work harder in the first period than in the second, the reverse 
occurs with the girls. Just as in the case of the fairly-quick girls, 
the percentages of increase and decrease in the working-rate of the 
slow boys and girls of different ages from I to If and from II to III, 
do not give rise to any further discussion. For the boys, with the 
exception of those of 8 years, these percentages are approximately 
constant. This constancy is however not noticeable among the slow girls. 
It would be too bold to draw any conclusions from the changes 
in the working-rates in connection with the influence exerted by 
the various factors that come into play with persistently continued 
labour, such as the start, the adaptation, practice, fatigue, abrupt 
instinctive actions of the will, voluntary concentrations of longer 
duration, the finish etc.') The task our experimental subjects were 
directed to perform, was too simple and too uniform for such con- 
clusions. Similarly our inquiry does not afford reliable evidence 
relative to the problem of the working-types. Moreover, the factors 
governing the working-process and to whose interference the differ- 
ent types owe their existence, lacked scope to display the irinfluence to 
the full during the comparatively short period required for our 
experiments. Nevertheless some of the above regularities may be 
classed with one of the types distinguished by Mrumann from a 
quantitative point of view with persistently continued labour Mev- 
1) Cf. Rivers und KRAEPELIN: Ueber Ermiidung und Erholung, Psychologische 
Arbeiten 1, blz. 636 en 639; LrypLEy: Ueber Arbeit und Ruhe. Ibidem 3, blz. 
513; v. Voss: Ueber die Schwankungen der geistigen Arbeitsleistung. lbidem 2. 
blz. 399. 
