26 DANIEL WILSON ON THE RIGHT 
the viscera, and the consequent increase of circulation thereby transferred from the one 
side to the other. But the relative position of the heart is so easily determined in the 
living subject, that it is surprising how much force has been attached to this untenable 
theory by eminent anatomists and physiologists. Another, and more generally favoured 
idea, traces to the reverse development of the great arteries of the upper limbs a greater 
flow of blood to the left side; while a third ascribes the greater muscular vigour directly 
to the supply of nervous force dependent on the early development of the brain on one 
side or the other. 
So far as either line of argument prevails, it inevitably leads to the result that the 
preference of the right hand is no mere perpetuation of convenient usage, matured into an 
acquired, or possibly an hereditary habit; but that it is, from the first, traceable to innate 
physical causes. This, as Sir Charles Bell conceives, receives confirmation from the fact 
already referred to, that right or left-handedness is not restricted to the hand, but affects 
the corresponding lower limb, and, as he believes, the whole side; and so he concludes 
thus: “On the whole, the preference of the right hand is not the effect of habit, but is a 
natural provision; and is bestowed for a very obvious purpose.” Nevertheless, the argu- 
ment of Sir Charles Bell is, as a whole, vague, and scarcely consistent. He speaks 
indeed of right-handedness as “a natural endowment of the body,” and his reasoning 
is based on this assumption. But much of it would be equally explicable as the result of 
adaptations following on an acquired habit. Its full force will come under consideration 
at a later stage. Meanwhile it is desirable to review the various and conflicting opinions 
advanced by other inquirers. 
The theory of Dr. Barclay, the celebrated anatomist, is thus set forth by Dr. Buchanan, 
from notes taken by him when a student: “The veins of the left side of the trunk, and of 
the left inferior extremity, cross the aorta to arrive at the vena cava; and some obstruc- 
tion to the flow of blood must be produced by the pulsation of that artery.” To this Dr. 
Barclay traced indirectly the preferential use of the right side of the body, and especially 
of the right hand and foot. “All motions,” he stated, “produce obstruction of the cireu- 
lation; and obstruction from this cause must be more frequently produced in the right 
side than the left, owing to its being more frequently used. But the venous circulation 
on the left side is retarded by the pulsation of the aorta, and therefore the more frequent 
motions of the right side were intended to render the circulation of the two sides uniform.” 
The idea, if correctly reported, is a curious One, as it traces right-handedness to the excess 
of acompensating force for an assumed inferior circulation pertaining naturally to the 
right side ; and incidentally takes into consideration an abnormal modification affecting 
the development or relative disposition of organs. Both points have been the subject of 
more extended consideration by subsequent observers. It is curious, indeed, to notice 
how physiologists and anatomists have shifted their ground, from time to time, in their 
attempts at a solution of what has been very summarily dismissed by others as a very 
simple problem; until, as Dr. Struthers remarks, it “has ceased to attract the notice of 
physiologists only because it has baffled satisfactory explanation.” 
The eminent anatomist, Professor Gratiolet, turned from the organs in immediate 
contact with the arm and hand, and sought for the source of right-handedness in another, 
and as I incline to think, truer direction ; though he only presented a partial view of this 
aspect of the case. According to Professor Gratiolet, in the early stages of fætal develop- 
