rH£ m^E OF LAND LIFE 39 



velopment of the brain. It is a sort of course of manual train- 

 ing in the use of eye and hand. 



In leaping from tree to tree eye and brain must see, meas- 

 ure and recognize exactly the direction, distance and strength 

 of the branch and the right point to be grasped. The body 

 must be hurled in exactly the right direction with the proper 

 amount of force. Hand and arm must be extended so as to 

 grasp the right point at the critical time. All this series 

 of observations and complex movements is probably, or may 

 be, worked out and completed with little conscious thought. 

 But the capacity for executing the movement has crystallized 

 out of a long series of experiments, and demands an exceed- 

 ingly complex brain for its performance. We do not won- 

 der that the anthropoid brain shows us a clear ground plan 

 of the brain of man with all its centers represented, though 

 often very incompletely. 



The process of evolution began with organs of digestion 

 used mainly to supply material for reproduction. The whole 

 aim of life seemed to be to increase and multiply, to exist and 

 survive. Then muscles crept in as means of getting food 

 and escaping danger. These occur at first as heavy masses of 

 trunk muscles giving at best only writhing locomotion. Then 

 appendages appear at first mere unjointed fins like paddles. 

 Then jointed appendages arise, at first weak, short and clumsy, 

 then strengthening and lengthening with steady increase of 

 freedom and precision in the movements of different parts, 

 especially of the distal parts as evolution shifts its field from 

 the stout heavy clumsy fundamental muscles of the trunk and 

 shoulder to the numerous small and fine muscles of hand and 

 finger. The ape has learned to use the hand as a whole 

 grasping organ, it was left to man to develop the vast variety 

 of movements and their combinations so characteristic of the 

 skilled artisan or technician. 



Every increase in muscle means and demands a corres- 

 ponding enlargement of the nervous system. Increased num- 

 ber of finer muscles and combinations of more precise move- 

 ments demands a larger number of more complex centers 



