IV RIGHT-HANDEDNESS 159 



condition could depend on it. There can, in my opinion, be 

 no doubt that the elongation in fact depends on mechanical 

 causes — that as the intestine in a drunkard is shortened during 

 his life, so it has been mechanically lengthened in the 

 vegetable-feeding animal by the greater quantity of food 

 taken ; and the new character has been inherited, so that now 

 it is looked upon by one zoologist as a specific distinction. 



It is a very remarkable fact that nearly all men use the right 

 arm much more than the left. Since all races of men, even 

 the most remote and most uncivilised, have this habit, we 

 cannot suppose that it has simply been acquired by practice, 

 and thus become hereditary. It is more probable that there 

 is something in the structure of the body, e.g. in the direction 

 and force of the course of the nutrient liquids, which gives 

 the right side of the body its superiority, if the mere position 

 of the heart towards the left is not the determining cause, on 

 account of the greater disturbance which that organ would 

 suffer if the left arm were chiefly used. Cases of left- 

 handedness rather favour than contradict such a supposition, 

 for in these cases parents and teachers have taken trouble 

 enough to train children to the usual habit, but in vain. 



It is to be supposed that this reverse habit is due to 

 congenital reversion of nutritive relations, such as that pro- 

 duced in the simplest way in complete reversion of the situs 

 viscerum. I do not know if it has been ascertained how far 

 left-handed people, e.g. left-handed swordsmen among students, 

 exhibit this inversion. It would be a praiseworthy task to 

 investigate whether some recognisable anatomical conditions 

 do not underlie their peculiarity of habit. 



Notwithstandincj this view of the connection between 

 organic conditions and the priority of the right arm, I believe 

 that the skill and strength of the latter, especially of the right 

 hand, are partly to be attributed to use. Martins, the editor 



