238 LAMARCK AND DARWIN 



naturally turns to great advantage in his argument for 

 evolution. Throughout the whole chapter Darwin's pre- 

 occupation with the problems of classification is clearly 

 manifest. 



On the question as to whether descent was mono- 

 phyletic or polyphyletic Darwin expressed no dogmatic 

 opinion. " I believe that animals have descended from at 

 most only four or five progenitors, and plants from an equal 

 or lesser number. ... I should infer from analogy that 

 probably all the organic beings which have ever lived on this 

 earth have descended from one primordial form, into which 

 life was first breathed " (p. 484). 



Darwin rightly laid much stress upon the morphological 

 evidence for evolution, 1 which he considered to be weighty. 

 It probably contributed greatly to the success of his theory. 

 Though he himself did little or no work in pure morphology, 

 he was alive to the importance of such work,' 2 and followed 

 with interest the progress of evolutionary morphology, incor- 

 porating some of its results in later editions of the Origin, 

 and in his Descent of Man (1871). 



In his morphology Darwin was hardly up to date. He 

 does not seem to have known at first hand the splendid 

 work of 'the German morphologists, such as Rathke and 

 Reichert ; he pays no attention to the cell-theory, nor to 

 the germ-layer theory. His sources are, in the main, 

 Geoffroy St Hilaire, Owen, von Baer, Agassiz, Milne- 

 Kdwards, and Huxley. 



Perhaps his greatest omission was that he did not give 

 any adequate treatment of the problem of functional 

 adaptation and the correlation of parts. It is not too much 

 to say that Darwin not only disregarded these problems 

 almost entirely, but by his insistence upon ecological 

 adaptation and upon certain superficial aspects of correlation, 

 succeeded in giving to the words " adaptation " and " corre- 



1 See his Letters, passim. 



' Writing to Huxley on the subject of the hitter's work on the 

 morphology of the Mollusca (1853), he says : "The discovery of the 

 type or 'idea' (in your sense, for I detest the word as used by Owen, 

 Agassiz & Co.) of each great class, I cannot doubt, is one of the very 

 highest ends of Natural History." More Letters, ed. F. Darwin and 

 A. C. Scward, 1903, i., p. 73. 



