INTRODUCTORY 



of animals and plants were immutably fixed. Linnaeus had 

 reduced the whole mass of names to order and the old fantastical 

 transformations with the growth of knowledge had lapsed into 

 discredit; the fixity of species was taken for granted, but not 

 till the overt proclamation of evolutionary doctrine by Lamarck 

 do we find the strenuous and passionate assertions of immutability 

 characteristic of the first half of the nineteenth century. 



It is not to be supposed that the champions of fixity were 

 unacquainted with varietal differences and with the problem 

 thus created, but in their view these difficulties were apparent 

 merely, and by sufficiently careful observation they supposed 

 that the critical and permanent distinctions of the true species 

 could be discovered, and the impermanent variations detected 

 and set aside. 



This at all events was the opinion formed by the great body 

 of naturalists at the end of the eighteenth and beginning of the 

 nineteenth centuries, and to all intents and purposes in spite 

 of the growth of evolutionary ideas, it remains the guiding 

 principle of systematists to the present day. There are 'good 

 species' and 'bad species' and the systematists of Europe and 

 America spend most of their time in making and debating them. 



In some of its aspects the problem of course confronted earlier 

 naturalists. Parkinson for instance (1640) in introducing his 

 treatment oiHieracium wrote, "To set forth the whole family of 

 the Hawkeweedes in due forme and order is such a world of 

 worke that I am in much doubt of mine own abilitie, it having 

 lyen heavie on his shoudiers that hath already waded through 

 them ... for such a multitude of varieties in forme pertaining 

 to one herbe is not to be found againe in rerum natura as I 

 thinke," and the same idea, that the difficulty lay rather in 

 man's imperfect powers of discrimination than in the nature of 

 the materials to be discriminated, is reflected in many treatises 

 early and late. 



It was however with the great ouburst of scientific activity 

 which followed Linnaeus that the difficulty became acute. 

 Simultaneously vast masses of new material were being collected 

 from all parts of the world into the museums, and the products 



