D. Heron 
383 
insanity in general or of an even broader degeneracy must always remain the 
first object of our studies. 
Any investigation of the inheritance of special types of insanity or degeneracy 
can only be carried out however on unselected material — on the records of com- 
plete families. The type of insanity is so closely related to the age of onset that 
any tendency to exaggerate the number of early cases, as in Dr Mott's material, 
will entirely vitiate the conclusions drawn. Thus Dr Schuster's conclusions as to 
the inheritance of special types of insanity based upon Dr Mott's data* must also 
be rejected on the above grounds. 
Dr Mott's index of relatives in London County Asylums is unfortunately of 
very little value in the study of inheritance in insanity. Progress can only come 
from the study of complete pedigrees in which every member of the family is 
entered, whether insane or normal, and the ages of the normal at the time the 
record was made are just as important as the age at onset of insanity in the insane 
members, for a statement that a young man of 20 has not been insane is of a 
very different degree of importance from the statement that a man of 70 has 
not been insane. 
In the papers I have cited the children of the insane if normal at 25 are 
advised to marry, and it is asserted that it is useless to attempt to discourage the 
reproduction of the insane since most of their children are born before the onset of 
insanity, and that we should rely on the Law of Anticipation to end or mend 
degenerate stocks. 
I have shown, I think, that the Law of Anticipation as applied to the insane 
has no foundation in the facts provided and that the advice given as to the marriage 
of the insane and of their normal offspring is fundamentally unsound and directly 
cacogenic. Much yet remains to be learnt regarding the inheritance of the insane 
diathesis, but no one who has studied the family histories of the insane can doubt 
that in inheritance we have by far the most important element in the production 
of insanity, and in view of all the facts it is the obvious duty of the Eugenist to 
discourage, rather than to encourage, procreation by the insane and even by those 
of their offspring who appear to be normal. 
* Report on the Statistical Investigation of Relative Cards, 21st Annual Keport of the London 
County Council Asylums Committee (1910), p. 95. 
49—2 
