Full text: papers communicated to the first International Eugenics Congress held at the University of London, July 24th to 30th, 1912

424Section IV.F. W. Mott. 
Figs. 16 & 17 represent diagrammatically the age incidence of first attack in parents and offspring. 
The first peak in the curve of the parent is due to the incidence of a larger number of cases of 
general paralysis in the male as compared with the female at this age period. It would be 
much more marked were it not for the fact that the cases of general paralysis among relatives 
are not numerous comparatively with other forms of insanity. This is as we should expect, 
for it is an acquired disease, and heredity plays a far less important part in its etiology than in 
the true insanities. It will be observed that the parent curves, male and female, attain their 
maximum in the involutional period. There is an obvious difference in the male and female 
parent curves. There is a greater incidence of insane mothers under 30 than fathers; this is 
due to puerperal cases, of which there were a fair number. These figures (16 and 17) are 
constructed upon the data contained in Table I. The abscissae represent the age periods and 
the ordinates the percentages of cases whose ages at the time of attack is first given. 
Collateral Heredity. 
The following table is compiled from 193 pairs of uncles and aunts with nephews and nieces 
in which only collateral heredity is manifested, and 231 pairs of uncles and aunts with nieces or 
nephews, in which are included those instances where one or both parents of the nieces and 
nephews are also insane. The figures denote the percentage of cases whose first attack occurred 
within the given age periods.Table II. 
Age Periods.Collateral Only.Collateral and Direct. 
Uncle 
or Aunt.Niece or Nephew.Uncle or Aunt.Niece or Nephew. 
Under 20 years5’22075‘225'5 
20-24 ,,3'1I9’23‘4177 
25-296'2i8’67-819-0 30-3412-917 *iI4-3I5'i 
35-39 »11-9124.12111’2 
40-4411'3124.10-44'3 45-49 »12-42‘II2'I2 "6 
50-5414-52‘I2'I17 55-5977IS8-62-1 6O-648-8—8*2— 
65-691 '5o'517o'4 
70-74 »10—1*3— 
75-793'i—26— 80_———
        

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