326 HABIT AND INTELLIGENCE. [chap. 



NOTE. 



FORMATION OP COMPLEX ORGANS. 



In answer to the objection that selection is inadequate to 

 produce a co-ordinated structure of many parts, Darwin ^ points 

 to the instance of the greyhound, all the parts of which are 

 together " adapted for extreme fleetness, and the running down 

 of weak prey;" yet the greyhound has been formed by selection; 

 hound. and the most competent selectors do not attempt to obtain all 

 kinds of excellence at once, but try for one point at a time.^ 

 This instance is conclusive as to the correlation of characters, 

 each of which may vary a little without necessitating variation 

 in the rest. But I do not think it -ttall apply to such an organ 

 as the eye. On this subject Darwin says : ^ — 



"A writer has recently maintained that 'it is probably no 

 exaggeration to suppose that, in order to improve such an organ 

 as the eye at all, it must be improved in ten different ways at 

 once. And the improbability of any complex organ being im- 

 proved and brought to perfection in any such way, is an impro- 

 bability of the same kind and degree as that of producing a 

 poem or a mathematical demonstration by throwing letters at 

 random on a table.' * If the eye were to be abruptly and 



1 Variation under Domestication, vol. ii. p. 221. 



2 " Tlie excellence of one sub-variety (of pigeon), the Almond Tumbler, 

 lies in the plumage, carriage , head, beak, and eye ; but it is too presump- 

 tuous in the beginner to try for all these points." The great judge above 

 quoted (J. M. Eaton) says : — " There are some young fanciers who are 

 over-covetous, and go for all the above five properties at once : they have 

 their reward by getting nothing." (Variation under Domestication, vol. ii. 

 p. 198.) Though these remarks are quoted of pigeons, Darwin evidently 

 means them to apply to the improvement of the breeds of all animals. 

 Compare what he says in p. 221 : " From what we know of the method 

 which different men follow in improving their stock — some chiefly attend- 

 ing to one point, others to another point, others again correcting defects 

 by crosses, and so forth." 



^ Variation under Domestication, vol. ii. p. 222. 



* Darwin here quotes from my opening address to the Belfast Natural 

 History Society, reported in the Northern Whig, Nov. 19, 1866. 



