44 Proceedings of the Royal Irish Academy. 



organ of prehension. The fact that its right fore-arm ought to be 

 stronger than its left, on the hypothesis given, is ignored ; and it would 

 be plainly antagonistic to the right conditions of flight, if one wing were 

 weaker than the other. Indeed nothing, perhaps, more clearly shows the 

 fallacy of the arguments in question than the fact that, whilst in birds 

 we find a series of grades intermediate between two carotids and one 

 sub-vertebral carotid — beginning with the median course of the right 

 common carotid (in parrots) proceeding to fusion in a common trunk, 

 and atrophy and disappearance of the right carotid beyond the point of 

 fusion^^ — there should yet be that constant and perfect equi-potence of 

 the fore-arms which is an essential condition to perfect flying. In 

 the Dabchick the left carotid is the larger; in the Emeu the right; in 

 the Apterix the left alone is found ; in the Flamingo the right is 

 single'^ — yet no con^esponding differences have been recorded in the 

 form and functions of the right and left limbs, anterior or posterior. 

 The argument from birds thus fails of its purpose, and only survives to 

 demonstrate that great vascular divergences may exist without being 

 peripherically expressed by lateral differences. 



III. Granting that a large amount of dextral predominance in man 

 at present exists, it is doubtful whether it exists so universally and so 

 completely as is assumed. Here I make elimination of persons distinctly 

 recognised as left-handed, and speak only of the general mass designated 

 right-handed people. Sir Charles BeU, Dr.W. Ogle, and others, maintain 

 that the predominance extends to the right foot, which, according to 

 Sir Charles Bell is first advanced in walking, and has a firmer tread : 

 he adds, " the horseman puts his left foot into the stirrup, and springs 

 from his right foot." Kow, there is here a patent contradiction : for if 

 in mounting, a man puts the left forward in order to spring from the 

 right, then in walking he puts the right forward in order to spring 

 from the left. But Bell, who accounts for his supposed fact, by the 

 assumption that it was so ordained in order that there should be no 

 hesitation as to which foot should be put forward, can never have 

 witnessed recruits being put through the first rudiments of military 

 di'ill. Untrained men show considerable diversity, and it is not with- 

 out teaching that the proper foot is advanced, which here, as in danc- 

 ing, happens to be the left. The left leg also is frequently shown ad- 

 vanced, in ancient art, e.g. in the Assyrian bas-reliefs. Those who are 

 acquainted with the habits of spade husbandly are aware that most 

 labourers employ the left foot in pressing the spade into the ground, 

 which proves that it has a tread sufiiciently firm for the purpose. If 

 the opera-dancer, as Sir Charles Bell observes, pei-forms "the most 

 difficult feats by the right foot," the organ-player, on the contrary, 

 gives the more difficult duty to the left foot. In proceeding to mount 

 a horse, we advance to his left side, take the reins in the left hand, 



IS Gegenbaiir: I. c. § 244. is Owens, vol. ii., § 154. 



