28 EXTERMINATION 



Extermination. We have seen that in later 

 periods the organisms have disappeared by degrees 

 and [perhaps] probably by degrees in earlier, and I 

 have said our theory requires it. As many naturalists 

 seem to think extermination a most mysterious cir- 

 cumstance 1 and call in astonishing agencies, it is well 

 to recall what we have shown concerning the struggle 

 of nature. An exterminating agency is at work with 

 every organism : we scarcely see it : if robins would 

 increase to thousands in ten years how severe must 

 the process be. How imperceptible a small in- 

 crease : fossils become rare : possibly sudden exter- 

 mination as Australia, but as present means very 

 slow and many means of escape, I shall doubt very 

 sudden exterminations. Who can explain why some 

 species abound more, why does marsh titmouse, or 

 ring-ouzel, now little change, why is one sea-slug 

 rare and another common on our coasts, why one 

 species of Rhinoceros more than another, why is 

 (illegible) tiger of India so rare? Curious and 

 general sources of error, the place of an organism is 

 instantly filled up. 



We know state of earth has changed, and as 

 earthquakes and tides go on, the state must change,- 

 many geologists believe a slow gradual cooling. Now 

 let us see in accordance with principles of [variation] 

 specification explained in Sect. n. how species would 

 probably be introduced and how such results accord 

 with what is known. 



other." The historian would discover that the inhabitants of the lower 

 town were Greeks while those of the upper one were Italians. But he 

 would be wrong in supposing that there had been a sudden change from 

 the Greek to the Italian language in Campania. I think it is clear that 

 Darwin's metaphor is partly taken from this passage. See for instance (in 

 the above passage from the Origin) such phrases as "history... written in a 

 changing dialect" "apparently abruptly changed forms of life." The 

 passage within [ ] in the above paragraph : "Lyell's views as far as 

 they go &c.," no doubt refers, as Professor Judd points out, to Lyell not 

 going so far as Darwin on the question of the imperfection of the geological 

 record. 



1 On rarity and extinction see Origin, Ed. i. pp. 109, 319, vi. pp. 133, 461. 



