ON THE GENETIC VIEW OF NATURE. 



337 



this idea, the whole work of classification has since 

 Darwin's time been taken up anew ; and though it is 

 probably premature to fix upon any elaborate scheme 

 as likely to afford a correct view of the main lines 

 of descent in the two great realms of animal and 

 plant life, single pedigrees, such as those of the rhino- 

 ceros and the horse, have, with the assistance of the 

 geological record, been successfully worked out, the 

 missing links having unexpectedly turned up. 1 



In addition to this great service of directing the 

 glance of the naturalist outside, and of helping to over- 

 come the bewildering effects which the aspect of nature 

 must produce on every one who is not prepared for 

 research by some definite aim and a distinct habit of 

 reasoning, the Darwinian spirit has further proved its 

 usefulness by the great increase of our knowledge of 

 the things and phenomena of nature which has taken 



" It is certain that, before 

 the theory of descent was accepted 

 or even discussed, genealogical trees 

 were used to represent possible 

 relationships among human races, 

 or possible affinities among animals. 

 It was used as a ' graphic ' way of 

 expressing classification, and was 

 true just in proportion as the 

 classification was true. The uat- 

 urali.st traveller, Peter Pallas, was 

 one of the tir.st to use it to express 

 affinities among animals, though 

 it is possible he saw a deeper 

 meaning in his symbol. But when 

 the theory of descent took hold 

 on men's minds, the genealogical 

 tree became more than a graphic 

 register of affinities, it was used 

 to express the supposed facts of 

 descent. To Ernst Haeckel be- 

 longs the credit, or, as some critics 

 would say, the responsibility, of 



VOL. II. 



introducing the use of genealogical 

 trees into zoology and botany. 

 In his ' Generelle Morphologie 

 (1866) and in his ' Schopfungs- 

 geschichte' (1868, 9th ed. 1897), 

 he displayed numerous genealogical 

 trees designed to show the descent 

 of various stocks and types of ani- 

 mals and plants. There can be 

 no doubt that in so doing he 

 focussed the idea of descent into 

 vividness, and, by the very definite- 

 ness of the notation, forced natural- 

 ists to a criticism of the reality 

 of the supposed lines of descent. 

 Prof. L. von Graff says of Haeckel's 

 ' Stammbiiume,' ' There is due to 

 them the immortal credit of having 

 given the first impetus to the 

 grand revolution in the animal 

 morphology of the last decades ' " 

 ( J. A. Thomson, ' The Science of 

 Life,' 1899, p. 15). 



