136 LIFE ON THE EARTH. 



stages of generation and growth, of decay and death. 

 The brain, as the organic minister to the mind, is the 

 part to which we look with deepest curiosity. Though 

 certain structural differences have been indicated, the 

 main and most obvious distinction between the brain 

 of the anthropoid apes and that of man is the difference 

 of size and weight. Without quoting the various facts 

 derived from Wagner and other enquirers, it is enough 

 to know that the cubic capacity of the largest go- 

 rilla skull yet examined is less than half that of the 

 average human cranium. It may be that molecular 

 differences, unseen by us, enter into and modify the 

 cerebral functions. But the fact still remains certain 

 that this condition of quantity in the brain plays a part 

 very essential in the relation of members of the animal 

 world, including man, both individually and distributed 

 into races of men. And the conclusion is more striking 

 as we descend in the scale of being, and find decrement 

 of brain associated throughout with decreasing intelli- 

 gence, and the substitution of those instincts which 

 become in the end the totality of life. 



We can in nowise reason upon this relation of size 

 and weight to the cerebral powers. Here, as in all that 

 concerns the connexion of the brain with the mental 

 functions, we have barely reached the mere rudiments 

 of knowledge. The same may be said of those cere- 

 bral convolutions the presence and complexity of 

 which are so remarkable in man, and which in the 

 higher quadrumana differ less from the human type 

 than they do from that of the lemurs, the lowest of 

 this order. This part of structure we can in nowise 



