THE EVIDENCE FROM DEVELOPMENT. 



195 



FIG. 1 06. SEA-URCHINS. 



sents more than an abbreviated and condensed summary of ancestral 

 conditions ; while this summary is often strangely modified by varia- 

 tion and adaptation to conditions ; and it must be confessed that, in 

 most cases, we can do little better than guess what is genuine 

 recapitulation of ancestral forms, and what is the effect of compara- 

 tively late adaptation. The only perfectly safe foundation for the 

 doctrine of Evolution," continues Huxley, " lies in the historical, or 

 rather archaeological, evidence 

 that particular organisms have 

 arisen by the gradual modifica- 

 tion^of their predecessors, which 

 is furnished by fossil remains. 

 That evidence is daily increas- 

 ing in amount and in weight; 

 and it is to be hoped that the 

 comparison of the actual pedi- 

 gree of these organisms with 

 the phenomena of their deve- 

 lopment may furnish some 

 criterion by which the validity 



of phylogenetic conclusions (or race-development), deduced from the 

 facts of embryology alone, may be satisfactorily tested." 



A survey of some typical groups of animals in relation to their 

 development will provide 

 us with satisfactory means 

 of judging how far and how 

 plainly the history of the 

 individual repeats that of 

 its race. Turning firstly to 

 some fields of lower life, 

 we may select the class 

 {Echinodermata) repre- 

 sented by the Starfishes 

 {Fig. 107), Sea-urchins 

 -(Fig. 106), Sea-lilies (or 

 Crinoids) (Fig. 109), and 

 Sea-cucumbers (Fig. 108), 

 as a starting-point for our 

 inquiries. There is little 

 need that a list of zoological 

 characters should be enu- 

 merated by way of impress- 

 ing the idea of the varied FlG - ^.-STARFISHES; 

 appearance of the animals 

 just mentioned. But it may be remarked that, firstly, they all exhibit 



O 2 



