The Logic of Evolution 



tern. A digestive system always remains com- 

 paratively simple. A sack or tube with a few 

 glands Is all that is needed. The reign of diges- 

 tion may have been short. Muscle and skeleton 

 are far more complex, capable of greater vari- 

 ety in amount, form, structure, and grouping. 

 Their capacities for improvement are many and 

 great. The reign of muscle lasted for ages. 

 The era of mind Is only begun. We know not 

 what we shall be. But the possibilities of mental 

 evolution are practically unlimited; they may be 

 infinite. The era of mind and the reign of its 

 higher powers, the supremacy of the highest 

 motives. Is sure. Its dynasty is secure. No 

 other system In the body can dispute Its place 

 and right. 



Animals and men have tried the experiment of 

 reversing this logical sequence of ruling func- 

 tions. Parasites and sessile animals have made 

 the muscles serve digestion. Men frequently 

 make mind the servant to the gratification of 

 lower powers. The experiment has always re- 

 sulted in degeneration and usually in extinction. 



The rule or dominance of functions Is suc- 

 cessive, but they are all present In the first pro- 

 tozoan. They are of equal age. The digestive 

 6 67 



