ALCOHOL, DISEASE, AND HEREDITARY DEFECTS 287 
But granting these groups dealt with are not representative 
of the general population, this fact is irrelevant, as Pearson has 
urged, so long as it has not been shown shown that for each group 
the alcoholic and non-alcoholic parents do not belong to heredi- 
tarily differentiated classes. Pearson claims that his critics have 
not shown that this is the case, and he has furnished evidence that 
so far as wages and choice of trades are concerned, there is no 
marked difference between the alcoholic and non-alcoholic sec- 
tions. It may be urged, a@ priori, that if a group which works 
against a handicap of alcohol attains an efficiency equal to that 
of another group not so handicapped, the former must be the 
better hereditary material, but we have no statistical proof of 
this in the present case. 
Where we are dealing with the parents of defective children, 
as in the Manchester data, there is of course the possibility, 
especially in the light of the experiments of Stockard, that the 
sober parents produce defective children because they are of 
defective stock, while a part of the alcoholics do so because they 
are alcoholic. These possibilities are mentioned not as a criticism 
of the memoir in question, but as showing the extreme difficulty of 
solving biological problems which are complicated by so many 
social factors. As the studies of extreme alcoholism have shown, 
extreme alcoholism itself serves to distinguish biologically one 
class from another. In view of the graded character of mental 
defect at what point does alcohol cease to have this segregating 
effect? An occasional or moderate use of alcoholic beverages is 
perhaps no more indicative of mental peculiarities than being a 
teetotaler, ifasmuch. But as the use of alcoho! imcreases it comes 
to be more of a mark of a hereditarily defective stock. It is not 
improbable that, as Pearson suggests, the parents of the Edin- 
burgh and Manchester school children failed as a rule to develop 
that degree of alcoholism which is associated with mental defect. 
The apparent discrepancy between the results of the First Study 
and the Studies on Extreme Alcoholism is explained on the ground 
that ‘‘the mentally defective became extreme alcoholists, ine- 
briates in constant conflict with the police because the mental de- 
