F. W. Mott.Medicine and Eugenics.403
possible to institute a factorial analysis of an individual.” How far such
analysis can be carried we do not yet know, but we have the certainty that
it extends far, and ample indications in supposing that we should probably
he right in supposing that it covers most of the features, whether of mind or
body, which distinguish the various members of a mixed population like that
of which we form a part. From such a representation we pass to the
obvious conclusion that an individual parent is unable to pass on to off
spring a factor which he or she does not possess. Since those individuals
only which are possessed of the factors can pass them on to their offspring,
so the offspring of those that are destitute of those elements do not acquire
them in subsequent generations, but continue to perpetuate the type which
exists by reason of the deficiency. It should be explicitly stated, however,
that in the case of the ordinary attributes of normal men we have as yet
unimpeachable evidence of the manifestation of this system of descent for
one set of characters only, namely, the colour of the eyes. Moreover,
if the evidence as to normal characteristics of man is defective—which in
view of the extreme difficulty of applying accurate research to normal
humanity is scarcely surprising—there is in respect of numerous human
abnormalities abundant evidence that a factorial system of descent is
followed.” (Bateson: Biological Fact and the Structure of Society.)
This may be, as Bateson claims, true for certain well defined abnormali
ties, e.g., polydactylism, brachydactylism, xeroderma pigmentosa, or
for night blindness, but as applied to the inheritance of a diathesis or
tendency, e.g., the neuropathic, Mendelian proportions are not shown as a
rule, although there is evidence of segregation of the factor underlying the
diathesis or tendency.
With this brief introduction to my subject, allow me to consider the
problem of Heredity and Eugenics in relation to insanity. Let me first
define my terms : Heredity has been defined by Thomson as “ the genetic
relation between successive generations, and inheritance includes all that the
organism is or has to start with in virtue of its hereditary relation.”
Heredity is a relation in successive generations which is sustained by a
more or less visible material basis, the germinal substance. Eugenics is
the science of racial improvement by the application of the laws of
heredity, viz., by encouraging the survival and the propagation of the
fittest in all classes of society, and by seeking to cut off the lines of
inheritance of the unfit in all classes of society. However, we do not
know enough about human genetics to predict always the fittest and the
unfittest. Some of the greatest men the world has seen have sprung
from the most humble and unknown stocks. Eugenics, therefore,
should aim at giving every individual that is worth preserving in every
class a chance of survival. A living wage, enough to ensure a sanitary
dwelling and a sufficiency of nourishing food for parents and family, should
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