D. Heron 
379 
at tlie age of 25 may safely marry. In an address delivered before the First 
International Eugenics Congress*, he said: " You will observe that 47*8 7o of the 
500 offspring had their first attack (of insanity) at or before the age of 25 years 
and as you see in the curves of parents and offspring, the liability of the child of 
an insane parent becoming insane tends rapidly to fall. Now besides the fact 
that this shows Nature's method of eliminating unsound elements of a stock, 
it has another important bearing, for it shows that after twenty-five there is a 
greatly decreasing liability of the offspring of insane parents to become insane 
and therefore in the question of advising marriage of the offspring of an insane 
parent this is of great imjiortance. Sir George Savage recently said that this 
statistical proof [sic !] of mine entirely accorded with his own expei'iences, and that 
if an individual who had such an hereditary history had passed twenty-five and 
never previously shown any signs (of insanity) he would probably be free and he 
would offer no objection to marriage." 
Now I entirely fail to understand how anyone could recommend marriage in 
such cases, even on Dr Mott's own figures; for if it be true that 48 7o become 
insane before 25, it must be equally true that 52 ''/^ become insane after that age 
and this very important point seems to have been forgotten. These figures, 
however, are taken from Dr Mott's selected data, selected in such a way that the 
early cases are enormously exaggerated. Until Dr Mott publishes a series of 
complete pedigrees, it will be safer to assume that the age at onset of insanity 
among the offspring of insane parents does not differ widely from that of all 
admissions to Asylums and there we find that only 21 '7o become insane before 25, 
and 79 7„ after 25. 
But surely at a Eugenics Congress of all places some thought might have been 
given to the mental condition of the children resulting from such matings, before 
advising marriage. It would not have been difficult forDr Mott to have extracted 
all the available cases of this kind from his collection of pedigrees, i.e. all cases in 
which an individual had an insane parent and was normal at the age of 25, and so 
have discovered the probable fate of the offspring from such matings. 
Unfortunately the details given by Dr Mott regarding his pedigrees are usually 
so scanty that little use of them can be made, but two at least show the danger of 
the matings Sir George Savage and he sanction ; these two pedigrees were given 
by Dr Mott in his lecture on Heredity in JRelatioii to Insanity, delivered to the 
members of the London County Council. The first is shown in Fig. 14. (It 
appeared as Fig. 11, p. 18 of Dr Mott's lecture.) In the first generation a man 
who became insane at 70 had four children. The eldest, a girl, became insane at 
68 and was therefore normal long after the age of 25. Dr Mott does not state 
whether the marriage of this woman preceded or followed the onset of insanity in 
her father, but even if her father had become insane before her marriage, Dr Mott 
* Problems in Eugenics,]). 425. This is one of many illustrations of the evil done by that Congress; 
attention was directed and much weight given to hasty statements and ill-digested material. 
