MIRACLES OF SCIENCE 



plant. If the divergent forms that now exist in- 

 sects, fish, reptiles, birds, mammals have indeed 

 been produced from the same lowly common ances- 

 tors by such slow processes of variation, the time 

 required for the evolution of existing races must ob- 

 viously be enormously long. 



Some students of the earth's rocky structure have 

 doubted that the actual lapse of geological ages is 

 sufficient to justify the theory of evolution through 

 the cumulative effect of slight variations. Geological 

 time is assuredly long; but is it long enough? The 

 biologists said that it must be; many geologists de- 

 nied that it could be. 



A possible solution of the controversy has recently 

 been found in a modification of the Darwinian theory 

 suggested by Professor Hugo de Vries, of Amster- 

 dam. The studies of this far-sighted experimental 

 botanist convinced him that the "spontaneous varia- 

 tions" on which evolution works are often much 

 more pronounced deviations from "type" than had 

 usually been assumed. From seed-pods of the same 

 plant may come individual plants that differ among 

 themselves not only slightly, but sometimes very 

 radically. In exceptional cases, as Professor de Vries 

 discovered, the deviation may be so marked that one 

 of the plants may fairly be regarded as constituting 

 a new race or "elementary" species. Such a depar- 

 ture from type, developed suddenly in a single gen- 

 eration, Professor de Vries spoke of as "mutation." 



The plant which furnished the most striking evi- 

 dence for the new mutation theory was found by 

 Professor de Vries near Amsterdam. It is a species 



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