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1911-12.] A Method of Measuring Mental Processes. 
for which he was treated in several institutions, each attack lasting a few 
weeks. Following each attack of excitement there was a short period of 
depression. 
Case VII. — Male, aged 59, single. Has been ill for fully thirteen years, 
and regularly every few months passes through a definite attack of excite- 
ment, after which he becomes abnormally quiet for a few weeks. 
Case VIII. — Male, aged 23, single. First broke down mentally at the 
age of 17, and has been treated on at least four occasions for severe attacks 
of excitement, from each of which he completely recovered. During his 
last attack he was on several occasions depressed for a few days. 
Case IX. — Male, aged 37, single. Has been ill for seven years. Has 
had regularly every few months attacks of excitement and depression, 
alternating with lucid intervals. 
Case X. — Female, aged 53, single. Has had at least two previous 
attacks of excitement, and her present illness, which has lasted since the 
age of 39, has been characterised by recurring attacks of excitement 
followed by short periods of depression and lucid intervals. 
Case XI. — Female, aged 29, single. Became depressed at the age of 26. 
Completely recovered. Three years later had an attack of severe excite- 
ment which lasted a few months, and from which she completely recovered. 
Case XII. — Female, aged 42, single. Had her first attack of depression 
at the age of 20, and since then has had several attacks of excitement and 
depression with lucid intervals, and each lasting from a few weeks to some 
months. 
Case XIII. — Male, aged 55, single. Had a slight attack of depression 
at the age of 50, from which he recovered. Had a similar attack at the 
age of 55 and again recovered. For at least thirty years of his life he 
was liable for a few days at a time to mild phases of restlessness and 
excitability. 
Case XIV. — Female, aged 23, single. Had her first attack, which was 
one of excitement, at the age of 20, from which she recovered ; became 
depressed three years afterwards, and again recovered after a few 
months. 
Case XV. — Female, aged 42, married. Had her first attack of 
depression at the age of 33. Nine years later again became depressed, and 
before completely recovering was mildly excited for a few weeks. 
Case XVI. — Female, aged 30, married. Became depressed at the age 
of 29, and from this she eventually recovered, although complete recovery 
was delayed on account of recurring attacks of depression. 
Case XVII. — Female, aged 16, single. Broke down first of all at the 
