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Proceedings of the Royal Society of Edinburgh. [Sess. 
reached the remarkable figure of 86 per cent. The normal improvability 
in the same period was only 53 per cent. The percentage improvement in 
Group C therefore exceeded the normal by 33 (Table VI.). 
In Group B the percentage improvement was at its height on the fourth 
day : it varied between 46 and 86, and averaged 68. The normal average 
for the same period was 41 per cent. — an increase of 27 per cent. The 
percentage improvement in Group B therefore exceeded the normal by 27 
(Table VI.). 
In Group A the percentage improvement was at its height on the third 
day ; 60*8 (Case 5), 58*2 (Case 15), 606 (Case 29). Their average was there- 
fore 59*8 per cent., and exceeded the normal by 24 per cent. (Table VI.). 
The Mental Work Curve. 
When the 30 cases of maniac depressive insanity were considered 
together, and their work as a group was mapped out from minute to 
Curve W. — Average Curve of Thirty Cases of Maniac Depressive Insanity. 
Showing percentage variation from minute to minute from the average rate 
of the test. 
no — ■ no 
95 9S 
minute, Curve W was obtained. In it the initial spurt was well marked, 
was of very short duration, and represented the highest working capacity 
attained in any one minute. A tendency to spurting was observed 
throughout the test; the spurts were frequent, but were not of great 
extent; indeed, they would be more accurately described as oscillations. 
If the initial spurt be excepted, several other spurts were present within 
the fifteen-minute interval : these spurts were not sustained ; the first two 
did not suffice to bring the output above the average level ; the last three 
were greater, and the greatest occurred just before the end. There was no 
true terminal spurt. The inconstancy of the rate was such that no one 
period could be taken as typical of the whole. The middle five-minute 
period was not more uniform than the rest. And there were two periods 
of maximum effort — during the first minute and during the last three 
minutes. 
