118 SOREN HANSEN 
Somewhat more fruitful is the study of the genetic relation between 
Dementia præcox and a number of other inherited diseases, which 
according to experience frequently occur in such families. The com- 
monest of these is imbecility in all degrees, from slight feeblemindedness 
to pronounced idiocy. Although our knowledge of these defects is still 
but faulty, it seems nevertheless certain, that the inherited forms — with. 
exception of the puerile Dementia identical with Dementia præcox — 
are handed down as dominant characters. «Since Dementia præcox 
usually occurs in individuals with normal or even superior intelligence, 
the disease cannot be regarded as a higher degree of imbecility or as the 
final result of a progressive degeneration; it seems rather that in the fa- 
milies, where Dementia præcox occurs along with imbecility, there must 
be a dominant common factor which along with an accessory, reces- 
sive special factor gives Dementia preecox, and along with other domi- 
nant or recessive factors gives either imbecility or quite different disea- 
ses. Since intelligence is not a single character, the lack of intelligence 
naturally cannot be regarded as such either and in so far it is very pro- 
bable, that the inherited forms of imbecility, which seem to differ only 
quantitatively, are in reality dependent on one or more polymeric fac- 
tors, but any closer investigation of this possibility will not bring us 
any further. ; 
Imbecility in the antecedents is not a necessary presupposition for 
the development of Dementia præcox in the successors, but it often 
appears in such a slight degree that it is overlooked and is not seldom 
masked by criminal tendencies or by the feminine equivalent of crimi- 
nality, moral looseness, but especially by drunkenness. Numerous 
cases of chronic alcoholism are in reality but the expression of im- 
becility, and in this we have the explanation why Dementia præcox 
and other inherited diseases very often appear to have their origin in 
drunkenness in the antecedents. In the rich material at my disposal 
in the extensive registers of the Danish Anthropological Committee of 
persons with inherited defects, for example, there is a family with two 
cases of Dementia præcox in first cousins which had nine cases of 
severe chronic alcoholism among the antecedents as well as a single 
case of imbecility in a younger individual. Not seldom, however, cases 
of Dementia præcox occur to all appearance quite’ isolated or, what 
amounts to the same thing genetically, in two or, though very rarely, 
in several of a family, but even this is not incompatible with the view, 
that the disease rests upon the contemporaneous presence of two — 
