DR. DRAPER'S LECTURE ON EVOLUTION. 183 



It is to be regretted that this phrase " natural selection " has been 

 introduced. It is very unscientific, very inferior to the old expression 

 adaptation. It implies a personification of Nature. It is anthropo- 

 morphic. But Nature never selects, never accepts or rejects, knows 

 nothing about duties, nothing about fitness or unfitness. Nature 

 simply obeys laws. 



Natural selection is thus supposed to perpetuate an organism 

 after adaptation to its environment has taken place. The change 

 implied by adaptation must precede it. It should be regarded rather 

 as a metaphorical expression than a scientific statement of an actual 

 physical event. 



Darwinism, therefore, does not touch the great question as to the 

 manner in which variation of organisms arises. It only teaches how 

 such variations are perpetuated. 



The publication of Humboldt's "Essay on the Geography of 

 Plants" (1805) first formally drew the attention of botanists to the 

 connection between the distribution of plants and the distribution of 

 heat on the surface of the earth. As an advance is made from the 

 equator toward the pole in either hemisphere, the mean annual tem- 

 perature declines, and in succession a series of vegetable zones is 

 encountered, merging gradually into each other, though each, where 

 best marked, is perfectly distinguished from its successor. In the 

 tropics there are the palms which give so striking a characteristic to 

 the landscape, the broad-leaved bananas, and great climbing plants 

 throwing themselves from stem to stem like the rigging of a ship. 

 Next follows a zone of evergreen woods, in which the orange and 

 citron come to perfection. Beyond this, another of deciduous trees, 

 the oak, the chestnut, and the fruit-trees of our orchards. Here the 

 great climbers of the tropics are replaced by the hop and the ivy. 

 Still farther is a belt of conifers, firs, larches, pines, and other needle- 

 leaved trees ; and these lead through a range of birches, becoming 

 more and more stunted, to a region of mosses and saxifrages, but 

 which at length has no tree nor shrub; and finally, as the perpet- 

 ual polar ices are reached, the red-snow alga is the last trace of vege- 

 table organization. 



A similar series of facts had long previously been observed by 

 Tournefort in an ascent of Mount Ararat. The distribution of vege- 

 tation from the base to the top of the mountain bears a general resem- 

 blance to the distribution from the base to the polar regions. These 

 facts were generalized by subsequent observers. It was established 

 that there exists an analogy between horizontal distribution on the 

 surface of the globe, and vertical distribution at different altitudes 

 above the level of the sea. Even in the tropics, if a mountain be 

 sufficiently high, a short ascent suffices to carry us from the charac- 

 teristic endogenous growths at its foot through a zone of evergreens 



