642 THE POPULAR SCIENCE MONTHLY. 



streams into primeval Niles, and Amazons, and Mississippis. Volcanic 

 forces uplifted here an Alpine chain, or depressed there a deep-sea 

 hollow. Sediment washed from the hills and plains, or formed from 

 countless skeletons of marine creatures, gathered on the sinking bed of 

 the ocean as soft ooze, or crumbling sand, or thick mud, or gravel and 

 conglomerate. Now upheaved into an elevated table-land, now slowly 

 carved again by rain and rill into valley and water-shed, and now worn 

 down once more into the mere degraded stump of a plateau, the crust 

 underwent innumerable changes, but almost all of them exactly the 

 same in kind, and mostly in degree, as those we still see at work imper- 

 ceptibly in the world around us. Rain washing down the soil ; weather 

 crumbling the solid rock ; waves dashing at the foot of the cliffs ; riv- 

 ers forming deltas at their barred mouths ; shingle gathering on the 

 low spits ; floods sweeping before them the country-side ; ice grinding 

 ceaselessly at the mountain-top ; peat filling up the shallow lake — these 

 are the chief factors which have gone to make the physical world as 

 we now actually know it. Land and sea, coast and contour, hill and 

 valley, dale and gorge, earth-sculpture generally — all are due to the 

 ceaseless interaction of these separately small and unnoticeable causes, 

 aided or retarded by the slow effects of elevation or depression from 

 the earth's shrinkage toward its own center. Geology, in short, has 

 shown us that the world is what it is, not by virtue of a single sudden 

 creative act, nor by virtue of successive terrible and recurrent cata- 

 clysms, but by virtue of the slow continuous action of causes still al- 

 ways equally operative. 



Evolution in geology leads up naturally to evolution in the science 

 of life. If the world itself grew, why not also the animals and plants 

 that inhabit it ? Already in the eager active eighteenth century this 

 obvious idea had struck in the germ a large number of zoologists 

 and botanists, and in the hands of Lamarck and Erasmus Darwin it 

 took form as a distinct and elaborate system of organic evolution. 

 Buffon had been the first to hint at the truth ; but Buffon was an emi- 

 nently respectable nobleman in the dubious days of the tottering mon- 

 archy, and he did not care personally for the Bastile, viewed as a place 

 of permanent residence. In Louis Quinze's France, indeed, as things 

 then went, a man who offended the orthodoxy of the Sorbonne was 

 prone to find himself shortly ensconced in free quarters, and kept there 

 for the ter.m of his naturaj existence without expense to his heirs or 

 executors. So Buffon did not venture to say outright that he thought 

 all animals and plants were descended one from the other with slight 

 modifications ; that would have been wicked, and the Sorbonne would 

 have proved its wickedness to him in a most conclusive fashion by 

 promptly getting him imprisoned or silenced. It is so easy to confute 

 your opponent when you are a hundred strong and he is one weak unit ! 

 Buffon merely said, therefore, that if we didn't know the contrary to 

 be the case by sure warrant, we might easily have concluded (so falli- 



