SiGERSON — On Dextral Pre-eminence. 47 



the right hand, which, hy constant practice, became the stronger. A 

 tendency to develop in this direction was transmitted by inheritance. 



This opinion is opposed to the view of Sir Charles Bell, who, 

 straining the doctrine of design, considered that dextral preference 

 was a "natural endowment," a "natural provision bestowed for a 

 very obvious purpovse" — namely, that "there should be no hesitation 

 as to which hand is to be used or which foot ought to be put forward." 

 Not, evidently, having given this subject a sufficient share of that keen 

 observation which characterised his great intellect, he fell into some 

 errors, as I have already shown : such of his reasons as remain to be 

 met will give little difficulty. He argues that, " Everything being 

 adapted (to the right hand) in the conveniences of life — as, for exam- 

 ple, the direction of 1;he worm of the screw, or of the cutting end of 

 the augur— is not arbitrary, but relates to a natural endowment of the 

 body." Granting that it is not arbitrary, I deny that it is universal. 

 Anyone who possesses a Geneva watch is aware that it is necessary 

 to wind it, not from left to right, as home-made watches are wound, 

 but fi'om right to left. During a sojourn in Paris one may experience 

 vexation on account of this diversity in the theory and practice of 

 screws ; for, in. winding a home-made watch with a Prench watch-key, 

 the key (not being riveted) will unscrew itself, and come asunder in 

 two pieces. Sir Charles Bell's reason would hold that the "natural 

 endowment" of a right-handed Frenchman's body is the opposite of 

 our own. But he advances another and a still more curious argu- 

 ment, when he says : " He who is left-handed is most sensible to the 

 advantages of this adaptation from the opening of the parlour-door 

 to the opening of a pen-knife." Plainly, Sir Charles Bell must have 

 overlooked the fundamental law that a door-way is for exit as well 

 as for entrance. If you come in through a portal, the door of which 

 is " adapted" to the right hand, on going out again, the door will be 

 found on the left— or "adapted" to the left hand. Of this theory 

 one may say, Solvitur amhulando. 



IV. Proceeding for the moment on the hypothesis that primeval 

 man was ambidextrous, it remains to be considered in what way or 

 ways dextral specialisation became a fact. Do we owe what we 

 possess of it to inheritance wholly ? Is it entirely the result of in- 

 dividual acquisition during early life ? Or do we both inherit fi'om 

 ancestral acquisitions and personally acquire ? We may reject the first 

 supposition and the second. The first cannot be true, because it is 

 unquestionable that, by special use and action, a member becomes 

 more apt and strong within certain limits, and that this obtains as 

 regards the right hand. Neither can the second be correct, for it 

 ignores and excludes the principle of heredity, which is now well 

 established. "We, therefore, must admit an inherited tendency to 

 specialise the right arm for acts requiring strength, whilst we must 

 also insist on the existence of personal acquisition. Of this personal 

 acquisition an infinitesimal portion may accrete to the human stock, 



