CONVERGENCE OF EVIDENCE 899 



metamorphism — of mountain structures and consequent rapid erosion and 

 deposition. These periods of wide and profound disturbance, lying in the 

 background of earth history, because of their very remoteness are pro- 

 jected into one sphere of vision. Perception of distance and perspective 

 are lost — as in the stars v^hich spangle the firmament, showing by their 

 radiance their fiery activities, but giving no suggestion of the vast spaces 

 of empty cold which lie between. 



RELATIONS BETWEEN LAPSE OF TIME AND ORGANIC EVOLUTION 



Closely connected with this expanded view of terrestrial duration is 

 another problem which in conclusion should be touched upon — the rela- 

 tionship of geologic time to the progress of organic evolution. 



If life originated at an early period on this earth and was not derived 

 from germs driven by the pressure of light from other worlds, protoplasm 

 must have existed at first as mere molecules of very complex nature. 

 Possessing a power of assimilation, such molecules became colloidal aggre- 

 gates by virtue of adding to their substance,- at first totally without struc- 

 ture or differentiation. In our ignorance of the ultra-microscopic stages 

 of organization which lie between the protoplasmic molecule and the 

 visible structures, we are prone to slight the necessity for the evolution 

 of these stages which led up to the organization of the cell; yet in these 

 the foundations of all later progress were laid. Protoplasm had to be- 

 come differentiated and organized, chemically and physically. There had 

 to arise nucleus, cytoplasm, and cell wall; powers of photosynthesis, of 

 digestion and excretion, of irritability and contractility. This chemical 

 organization represents an adaptation to environment which must have 

 resulted from the selection of efficient variations out of numberless chance 

 chemical combinations. The initial preservation of the successfulr^proto- 

 plasmic combination was owing to the fact that the world was as yet 

 without predatory organisms. 



Most remarkable of all, perhaps, in this basal evolution was the estab- 

 ment of the principles of inheritance, residing in a marvelous mechan- 

 ism, by virtue of which the descendants start life with the capital of 

 efficiency acquired by their ancestors and sifted by selection through all 

 previous time. Without inheritance there could be no progress, but 

 powers of inheritance mean an incomprehensible complexity in the ultra- 

 microscopic structure of the cell. The chromatin threads in the single, 

 undifferentiated metazoan egg-cell detennine the differentiation and as- 

 semblage of the billions of daughter cells which build the adult body. 

 Considering the stages wliicli have to be passed through, the child is 



