458 
GENETICS: C. B. DAVENPORT 
the two series is fairly close — the greatest difference being an unexpected 
excess of choleric-melanchoHcs and corresponding deficiency of choleric- 
phlegmatics ; also an excess of calm-cheerful and deficiency of calm-phleg- 
matic. These discrepancies imply a rather slight error in the classifi- 
cation of the observed cases. 
We conclude, then, from our own data that the hypothesis is confirmed. 
In addition, an examination of the Kterature reveals clear evidence that 
a difference in the inheritance of extreme hyperkinesis (a dominant) 
and extreme hypokinesis (a recessive) has unconsciously been observed. 
And the differences in the conclusions of Rosanoff and Orr^ and Riidin^ 
concerning the inheritance of manic-depressive insanity — one regarding 
it as recessive and the other regarding it as sometimes dominant — are 
easily explained on the ground of its complex hereditary nature. 
The hereditary nature of temperament is demonstrated by the facts 
of the personal history of identical twins, as given by Gal ton. ^ 
There is reason for thinking that the different zygotic combinations of 
temperamental factors occur with different frequencies. A comparison 
of the relative number of matings in equally frequent kinds of zygotic 
combinations shows that some are much more common than expected, 
others much less. The mated pair rarely have the same zygotic 
temperamental formula. Two choleric or ' nervous ' persons frequently 
do not marry each other. Two melanchoKcs rarely intermarry. There 
is, in marriage, a selection against similar temperaments, i.e., a pref- 
erence for those of more or less markedly dissimilar temperaments. 
An analysis of the temperaments of suicides shows that they fall into 
the two types of the hyperkinetic (or impulsion) suicides and the hypo- 
kinetic (or depressed) suicides. Also, a family tendency to suicide by 
the same method is evident; but it is uncertain whether this is due 
chiefly to subconscious suggestion or to an hereditary bias. 
This study throws light upon the nature of the ' functional insanities ' 
and lends strong support to the view that they are syndromes whose 
elements are separately inheritable. 
Finally the study throws light upon the ' springs of conduct. ' Just 
what we shall, in any situation, do is determined by numerous factors, 
but the general nature of our reactions, whether violent or repressed — 
this is determined by the hereditary nature of our temperaments. The 
romantic and the classic t3^e of reacting, the hyperkinetic and the 
hypokinetic, the radical and the conservative, the feebly inhibited and 
the strongly inhibited constitute a dualism that runs through our whole 
population. 
