DIFFERENT IDEAS ABOUT SPECIES 59 



and limitations, will be attempted in the later pages of 

 this Address. 



Various conceptions of Species. 



In a letter to Hooker, Dec. 24, 1856, Darwin gave 

 a short account of the various definitions he had met 

 with. ' I have just been comparing definitions of species, 

 and stating briefly how systematic naturalists work out 

 their subjects. ... It is really laughable to see what 

 different ideas are prominent in various naturalists' 

 minds, when they speak of " species " ; in some, re- 

 semblance is everything, and descent of little weight — 

 in some, resemblance seems to go for nothing, and 

 Creation the reigning idea — in some, descent is the 

 key, — in some, sterility an unfailing test, with others it 

 is not worth a farthing. It all comes, I believe, from 

 trying to define the indefinable.' * 



As regards the work done by the systematist, we find 

 that Darwin did not agree with those of his friends who 

 thought that a belief in evolution would entirely alter its 

 character. Thus he wrote to Hooker, Sept. 25, 1853 : — 

 1 In my own work I have not felt conscious that dis- 

 believing in the mere permanence of species has made 

 much difference one way or the other ; in some few cases 

 (if publishing avowedly on the doctrine of non-per- 

 manence), I should not have affixed names, and in some 

 few cases should have affixed names to remarkable 

 varieties. Certainly I have felt it humiliating, discussing 

 and doubting, and examining over and over again, when 

 in my own mind the only doubt has been whether the 

 form varied to-day or yesterday (not to put too fine a point 

 on it, as Snagsby would say). After describing a set of 

 forms as distinct species, tearing up my MS., and making 

 them one species, tearing that up and making them 

 separate, and then making them one again (which has 

 happened to me), I have gnashed my teeth, cursed 

 species, and asked what sin I had committed to be so 

 punished. But I must confess that perhaps nearly the 



1 Life and Letters of Charles Darwin, London, 1887, vol. ii, p. 88. 



