CHAPTER XVI 



THE METHOD OF ORIGIN OF NEW SPECIES AND 

 STRUCTURES, AND THE CAUSES OF THEIR FITNESS 

 TO THE PLACES THEY LIVE IN 



Evolution and Adaptation 



F the various aspects which Nature presents to the 

 intellect of man, there are two of particular promi- 

 nence, — facts and explanations. Of these the greatest 

 by far are facts, — naked, stark, primitive, elemental, 

 cosmical facts. They are the raw material of science, and nothing 

 can replace them. But when one has made himself master of a 

 goodly mmaber thereof, and has arranged them in some kind of 

 preliminary classification, he soon comes to crave explanation of 

 the remarkable relations they are sure to exhibit. Explanation 

 is the office of Philosophy, and there is a Philosophy of Nature. 

 The phases thereof most important to the student of animals and 

 plants concern the origins of their multifarious kinds, of their 

 elaborate structures, and of their remarkable fitness to their 

 surroundings. There was a time when none of these were; now 

 they all are; when and how, in the interval have they arisen? 

 This is the great present problem of philosophical biology, and 

 one which the reader, fresh from his contemplation of the facts 

 and relationships set forth in the preceding pages, is now pre- 

 pared, and I hope eager, to attack. 



There are two great explanations, logically and historical!}^, of 

 the origin of species, structures, and adaptations, — viz.. Special 

 Creation and Evolution. The doctrine of Special Creation, held 

 almost universally down to a half century ago, maintained that 



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