1907.] on Dexterity and the Bend Sinister. 639 



highest excellence ; but the notable facts are that ambidexterity 

 which, if it has any utility, ought to be especially useful to them, has 

 not been seen amongst them and has neyer been cultivated by them, 

 and that, \yith a mere fractional deduction, all the art treasures of the 

 world have been the offspring of the right hand. 



The theories that have been advanced to account for right- 

 handedness have been numerous, ingenious, and some of them fantastic 

 enough. It has been ascribed to the machinations of the devil, to a 

 loss of balance in the body owing to the removal of a rib from Adam's 

 side while he slept ; and Aristotle attributed it to the fact (how he 

 arrived at a knowledge of it he did not say) that the blood that flows 

 to the right side is purer and hotter than that that flows to the left. 

 It would be instructive to traverse all of these theories, for in refuting 

 each of them we should obtain a glimpse of right-handedness from a 

 different point of view. But time permits me to mention one only 

 which has been revived of late, and in a modified version, still to 

 some extent holds the field. That is the theory of Dr. Buchanan 

 that right-handedness is due to certain mechanical advantages 

 possessed by the right side of the body. The right lung is larger 

 and more capacious than the left, and has three lobes instead of two, 

 so that when a deep inspiration, the necessary prelude of any great 

 muscular effort, is taken, a more stable basis of support is given to 

 the right upper \\m\). But more than that, the weight of the viscera 

 on the right side of the body, where lies the solid mass of the liver, 

 is considerably greater than that of those on the left side, chiefly 

 filled by the hollow viscera, the stomach and the intestines. The 

 difference amounts, according to the late Professor Struthers, to about 

 15 ounces, and although that estimate is probably too large, especially 

 when the stomach to the left is occupied by a heavy meal, there can 

 be no doubt that the centre of gravity of the body lies to the 

 right of the mesial line. According to Buchanan, this gives a bias to 

 the body like that of bowls that are oblate on the one side and prolate 

 on the other, and in the erect posture exerts an influence on attitude 

 and movements and gives a mechanical advantage to the right arm. 

 Right-handedness, he argued, is not a congenital attribute of man 

 transmitted from parent to offspring, but a personal habit picked up 

 during the individual life, as the result of the greater weight of the 

 right side. All infants, he said, are born ambidextrous and gradually 

 find out for themselves in using their hands that they have more 

 mechanical power on the right side. 



It is not difficult nowadays to perceive that Buchanan was 

 wrong. Infants are born ambidextrous in a sense — that is to say, 

 for the first few months of their lives they use both arms together. 

 But unmistakeable right-handedness declares itself about the eighth 

 month, l)efore the infant can have profited by experience or has 

 assimied the erect posture : and it would be as reasonable to maintain 

 that the emergence of its teeth is due to the use of its jaws as it is to 



