94 FOURTH GENERAL MEETING. 



calculated ratio ought to be increased by potentiation with a certain 

 unknown exponent expressing the complication of the structure, 

 which however appears to be dependent upon the relative quantity. 

 Man has four times as much brain as an anthropoid ape of equal 

 bulk. But F"lechsig has shown that the centres in the cerebral 

 cortex, to which certainly we have to ascribe the highest functions, 

 the association centres, connecting together centres belonging to 

 different senses, form in man the two-third part, in apes only the 

 half of the whole superficies of the cerebral cortex. Still a very 

 much more important difference is founded upon the fact that the 

 pyramidal cells of the cortex in the brain of man have more branches 

 than those in the brain of the ape. Thus the relative functional 

 value of man's brain in comparison to that of the ape ought to be 

 measured by a much higher number than four. 



Still, though representing but partially the real degree of brain 

 development, our relative cephalisation appears to be the most 

 important measure of that development as shown, since that by 

 reference to it the mammalia may be ranged in a natural scale. 



Thus it becomes apparent that it should be of the highest 

 importance to calculate the relative cephalisation of Pithecanthropus 

 erectns. 



I have already pointed out that on the mere evidence of his 

 cranial capacity, without taking into account the size of the body, 

 he may have belonged to the ape-tribe or to the human species. 

 It can be easily calculated how much the weight of the body of 

 Pithecanthropus ercctus should have been, had he had a relative 

 cephalisation equal to that prevailing in the Anthropoid apes. We 

 find nearly 230 kilogrammes. With a relative cephalisation equal 

 to that of Man on the other hand, given the cranial capacity, he 

 should only have weighed about 19 kilogrammes. 



Now we have the good fortune to possess in the femur a means 

 of estimating the body-weight with some approximation to accuracy. 



It is a fact, proven beyond any doubt, that the bones are adapted 

 to the forces acting upon them. The researches of H. Meyer and 

 others have shown indeed that even their inner structure is calcu- 

 lated to resist the forces trying to break them — to such an extent as 

 it ought to be theoretically according to the rules of mechanical 

 science. The solidity of any given bone depending, according 

 to certain formulae, upon its length and its thickness, and the forces 

 to which it is accommodated in nearly allied animals of similar 

 form but of very different size, being in some way proportionate to 

 the weight of the body, it must be possible to find a relation 

 existing between the length and the thickness of the homologous 

 bones and the body-weight. 



Now by comparing in the Leiden Museum skeletons of such 

 animals, of which the body-weights were approximately known, as 

 Lions with Cats, Beisa- with Pygmy-antelopes, I found in fact such a 

 relation, and can express it in figures. As an a posteriori argument, 



