156 THE GENESIS OF SPECIES [Chap. 



a species "unconscious selection, that is, the preservation 

 of the most useful or beautiful animals, with no intention 

 of modifying the breed." He adds : " But by this process 

 of unconscious selection, various breeds have been sensibly 

 chanL>ed in the course of two or three centuries." 



" Sensibly changed ! " but not formed into " new species." 

 ^Er. Darwin, of course, could not mean that s})ecies 

 gcncraUy change so rapidly, which would be strangely at 

 variance Avith the abundant evidence we have of the 

 stability of animal forms as represented on Egyptian 

 monuments and as showm by recent deposits. Indeed, 

 he goes on to say, — " Species, however, probal)ly change 

 much more slowly, and within the same country only a 

 few change at the same time. This slowness follows from 

 all the inhabitants of the same country being already so 

 well adapted to each other, that places in the polity of 

 nature do not occur until after long intervals, when 

 changes of some kind in the physical conditions, or 

 through immigration, have occurred, and individual dif- 

 ferences and variations of the right nature, by which some 

 of the inhabitants might be better fitted to their new 

 places under altered circumstances, might not at once 

 occur." This is true, and not only will these changes 

 occur at distant intervals, but it must be l)orne in mind 

 that, in tracing: back an animal to a remote ancestrv, we 

 pass through modifications of such rapidly increasing 

 numl)cr and importance that a geometrical progression 

 can alone indicate the increase of periods which such 

 profound alterations would require for their evolution 

 through " Natural Selection " only. 



Thus let us take for an example the proboscis monkey 

 of Borneo (Scmnopithccus nasal is). In Mr. Darwin's own 



