AN EXAMINATION OF SOME RECENT STUDIES OF THE 
INHERITANCE FACTOR IN INSANITY 
By DAVID HERON, D.Sc* 
In the last few yeai's a number of studies of the inheritance factor in insanity 
have been published in America, Germany and England. The value of investigation 
of such a topic cannot be overestimated. We are quite certain that the prevalence 
of insanity is not falling ; many of us indeed believe that the statistics suffice to 
demonstrate that it is substantially increasing, and that we can attribute this 
increase not in the first place to the intenser strain of modern life, but to the 
greater power of modern treatment to check or temporarily cure attack, and thus 
allow wider possibility of reproduction to members of affected stocks. Indeed the 
problem seems closely associated with an essential difficulty of modern civilisation, 
the greater protection of physically and mentally degenerate stocks unaccompanied 
by any adequate limitation of their thereby increased power of procreation ; the 
inheritance factor thus tends to aid the relatively greater survival of the socially 
unfit. The studies we have referred to would be of great importance from this 
aspect of eugenics if (i) the data were collected without conscious or unconscious 
bias, and (ii) the inferences drawn from them followed logically from the data thus 
collected. 
Unfortunately it is not only in the interpretation of statistics that adequate 
training is required. It is equally important that in the actual collection of thera 
we should proceed, not only free from the bias which arises from the hurried 
acceptance of dogmatic theories of heredity, but what is often still more needful, 
free from the bias which is almost certain to waylay our progress, if we have not 
initially considered with trained insight the fallacies which may result from our 
method of recording or even tabulating our material. The day of the amateur in 
science is gone ; no one now pays any attention to men who propound elaborate 
atomic theories or stellar hypotheses, without having had preliminary training in 
physical or astronomical science. There are still, however, some who appear 
willing to accept the statement of statistical data or the inferences drawn from those 
* This paper formed the second portion of a lecture given at the Galton Laboratory on March 3, 1914. 
