50 Proceedings of the Royal Irish Academy. 



Now, bear in mind that we have it demonstrated, by the case of 

 Sir Henry Holland and by other cases, that a personal acquisition, 

 positively known to have been the earning of the individual himself, 

 does fall off under circumstances of depression and exhaustion, and yet 

 may be easily regained. When, therefore, we discover that the pre- 

 dominant strength of the right arm is amenable to the same fate, and 

 subject to the same laws, we are compelled to conclude (having 

 already eliminated all interfering arguments) that this dextral predo- 

 minance is a personal acquisition also. 



Reasoning back, it would appear that Primeval Man was ambidex- 

 trous. Nothing in his structure prevented this condition or suggested 

 another. The simple occupations of the early world and those primitive 

 arts which yet persist suited either hand or engaged both. Gradually, in 

 the lapse of years, as occupations became more complex, the principle 

 of the division of labour became more and more acted upon, and the 

 functions of the hands became more specialised. This acquired habit 

 of specialisation was transmitted by inheritance, constituting a ten- 

 dency or predisposition in the offspring. As an aptness to learn 

 languages may be transmitted, but not the languages themselves ; so, 

 a tendency to use the right hand for feats of strength was bequeathed, 

 but not the strength itself. That is the acquisition of the individual. 

 The ambidextrous child repeats in every generation the condition of 

 the Primeval Man. 



