TBANSACTIONS OF SECTION H. 889 



can effect a similar movement de novo without the direct iutervention of external 

 impressions at all. Now it has been proved experimentally that the volitional 

 stimulus, which regulates the various movements of the body, starts from definite 

 portions of the brain according to the diflerent results to be produced. This locali- 

 sation of brain functions, though still far from being thoroughly understood, comes 

 very appropriately into use in this inquiry. From it we learn that the homology 

 which characterises the structural elements of the bodies of animals extends also 

 to the component parts of their respective brains. The law which differentiates 

 animals according to the greater specialisation of the functions of their various 

 organs has therefore its counterpart in the brain, and we naturally expect an 

 increase of brain substance in every case in which the functional activity of a 

 specific organ is extended. Thus the act of stitching with a needle and thread, 

 an act beyond the mental and physical capacity of any animal but man, would 

 entail a certain increase of brain substance, simply in obedience to the great com- 

 plexity of the movements involved in its execution, over and above that which 

 may be supposed to be due to the intellectual and reasoning faculties which 

 invented it. 



That man's brain and his intelligence are correlated to each other is a fact too 

 axiomatic to require any demonstration; nor can it be doubted that the relation- 

 ship between them is of the nature of cause and effect. Bat to maintain that the 

 amount of the latter is directly proportional to the size of the former is rather 

 straining the laws of legitimate inference. In drawing any general conclusion of 

 this nature from the bulk of brain substance, there are some modifying influences 

 which cannot be disregarded, such, for example, as the amount of cranial circula- 

 tion and the quality of the brain cells. But the determination of this point is not 

 the exact problem with which the evolutionist is primarily concerned. To him the 

 real crux in the inquiry is to account for the evolution of man's comparatively 

 large brain under the influence of existing cosmic forces. After duly considering 

 this pi'oblem, and casting about for a possible explanation, I have come to the con- 

 clusion that not only is it the result of natural laws, but that one of the main 

 factors in its production was the conversion of the upper limbs into true hands. 

 From the first moment that man recognised the advantage of using a club or a 

 stone in attacking his prey or defending himself from his enemies, the direct incen- 

 tives to a higher brain development came into existence. He would soon learn by 

 e.xperience that a particular form of club or stone was more suitable for his pur- 

 poses ; and if the desiderated object were not to be found among the natural 

 materials around him, he would proceed to manufacture it. Certain kinds of stones 

 would be readily recognised as better adapted for cutting purposes than others, 

 and he would select his materials accordingly. If these were to be found 

 only in a special locality, he would visit that locality whenever the prized 

 material was needed. Nor would it be an unwarrantable stretch of imagina- 

 tion to suppose that the circumstances would lead him to lay up a store for future 

 use. These simple acts of intelligence assume little more than may be seen in 

 the actions of many of the lower animals. Consciousness of his power to make 

 and to wield a weapon was a new departure in the career of man, and every repe- 

 tition of such acts became an effective and ever-accumulating training force. What 

 a memorable event in the history of humanity was the manufacture of the first 

 sharp stone implement ! Our sapient ancestor, who first used a spear tipped with 

 a sharp flint, became possessed of an irresistible power over his fellow men. The 

 invention of the bow and arrow may be parallelled with the discovery of gunpowder 

 and the use of cannon, both of which revolutionised the principles of warfare in 

 their respective ages. The art of making fire had a greater influence on human 

 civilisation than the modern discovery of electricity. The first boat was in all 

 probability a log — an idea which might have been suggested by the sight of an 

 animal clinging to a floating piece of wood carried away by a flood. To scoop this 

 log into a hollow boat was an afterthought. The successive increments of know- 

 iedge by which a single-tree canoe has been transformed into a first-class Atlantic 

 liner are scattered through the unwritten and written annals of many ages. In his 

 expeditions for hunting, fishing, fruit-gathering, &c., primitive man's acquaintance 



