THE PHANTOMS BEHIND US 



always with us, but where are the myriad earher 

 forms that were the antecedents of the present animal 

 life of the globe? True, the palaeontologist finds a 

 more or less disjointed record of them in the strati- 

 fied rocks and sees in a measure the course evolu- 

 tion has taken, but he does not actually see it at 

 work as does the astronomer. More than that, the 

 forces the astronomer deals with are mechanical 

 and chemical, but the biologist deals with a new 

 force called life that often reverses or defies me- 

 chanical and chemical forces, but which is yet so 

 identified and blended with them that we cannot 

 conceive it apart from them. The stomach does not 

 digest itself, nor gravity hold the blood in the lower 

 extremities. The tree lifts up its weight of fluids 

 and solids and holds aloft its fruit and foliage in 

 spite of gravity; its growing roots split and lift the 

 rocks; mosses and lichens disintegrate granite; vital 

 energy triumphs over chemical and mechanical 

 energy. 



Biological laws are much more subtle and diflScult 

 to trace and formulate than chemical and mechani- 

 cal laws. Hence the student of organic evolution 

 can rarely arrive at the demonstrable certainties in 

 this field that he can in the sphere of chemistry and 

 mechanics. It is very doubtful if life can ever be 

 explained in terms of these things. Life works 

 through chemical combinations and affinities, and 

 yet is it not more than chemistry.'^ It works with 



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