UTAH ACADEMY OF SCIENCES 61 
already established fact that in right-handed persons 
for example, the left-cerebral hemisphere dominates the 
right half of the body and also controls the speech move- 
ments. Since handwriting is a form of speech and 
directly involves the speech centers in the cerebrum, to 
change one’s handedness after the cerebral centers have 
become physiologically established, is to produce aberra- 
tions referred to. These facts and even the limited data 
accumulated make it morally incumbent upon the teacher 
as well as the parent to proceed cautiously in training the 
child who exhibits any left-handed tendencies whatso- 
ever. 
With increasingly complex and specialized mechan- 
ical environment calling more and more for manual skill 
and dexterity upon the part of vocational workers and 
others, the problem seems entitled to more than passing 
notice. The industrial worker or the soldier who loses 
his dextrous hand or arm must be fitted by society for 
economic independence and usefulness. Such rehabil- 
itation, it is obvious, can proceed only intelligently with 
some recognition and study of the complex neuro-mus- 
cular processes involved. It is hoped that the United 
States Surgeon’s General’s Office will sieze the oppor- 
tunity to contribute to the solution of this problem by a 
thoroughgoing analysis of its results and observations in- 
the matter of manual re-education. 
Such then are a few of the more important aspects 
of the problem of left-handedness. Let us turn our atten- 
tion now to a brief discussion of the available facts, 
theories, and opinions which together constitute our pres- 
ent stock-in-trade for an attack of the problem. 
While the median of the results of all investigations 
dealing with the prevalence of left-handedness, gives the 
distribution as 4% of the normal population, it is note- 
worthy that Ballard, Smith, Weber and Lombroso hold 
that the characteristic is more frequently found among 
males than females. Five other workers find left-hand- 
edness more frequent among delinquents, and Lattes 
finds it more prevalent among negroes. The wide dis- 
parity between the results of the various studies would 
seem to be due largely totwothings. First, a too narrow 
survey, and second, a questionable technique which in 
