TRANSITION UNDERLIES DIAGNOSIS 67 



And in difficult cases no two of them agreed in their 

 conclusions. Many passages in Darwin's correspondence 

 convincingly prove how essential an element is this con- 

 tinuity, and how inevitable is the dominance of the 

 subjective element. Thus he writes about his descriptive 

 work on Cirrhipedes to Hooker, October 12, 1849 : — 

 * I have of late been at work at mere species describing, 

 which is much more difficult than I expected, and has 

 much the same sort of interest as a puzzle has ; but 

 I confess I often feel wearied with the work, and cannot 

 help sometimes asking myself what is the good of spend- 

 ing a week or fortnight in ascertaining that certain just 

 perceptible differences blend together and constitute 

 varieties and not species. As long as I am on anatomy 

 I never feel myself in that disgusting, horrid, mi bono, 

 inquiring, humour.' ^ 



On another occasion, when Darwin was anxious to 

 ascertain the ' close species ' in the North American 

 Flora, and wrote for information to Asa Gray, he frankly 

 adopted the subjective criterion in order to explain exactly 

 what he meant. He wrote, June 8 [1855]: — 'The 

 definition I should give of a " close species " was one that 

 you thought specifically distinct, but which you could 

 conceive some other good botanist might think only 

 a race or variety ; or, again, a species that you had 

 trouble, though having opportunities of knowing it well, 

 in discriminating from some other species.' ^ 



Asa Gray's reply is also very interesting from the 

 same point of view. He wrote, June 30, 1855 : — ' Those 

 thus connected ' [he had bracketed the ' close species ' in 

 a list of the Flora], ' some of them, I should in revision 

 unite under one, many more Dr. Hooker would unite, 

 and for the rest it would not be extraordinary if, in any 

 case, the discovery of intermediate forms compelled their 

 union.' " 



Darwin was evidently in high spirits when he wrote 

 the following passage which bears on the same subject. 

 The Origin had been published on November 24, 1859, 



^ Life and Letters, vol. i, p. 379. "^ Ibid., vol. ii, p. 64. 



^ More Letters, vol. i, p. 421, Letter 324. 



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