i DEFECTS IN SKIN THEORY 51 



secret forces of vitality deal at their will 

 with outness and inness. The external 

 surfaces of one stage are folded in and 

 become most secret recesses at another. 

 Organs which are outside in one animal, 

 and are conspicuously flourished in the 

 face of day with exquisite ornament of 

 colour and of structure, 1 are in another 

 animal hid away and carefully covered 

 up. Nay, there are many cases in 

 which all these changes are conducted 

 in the same animal at different periods 

 of life, and during conscious and uncon- 

 scious intervals the whole creature is 

 re-formed to fit it for new surroundings, 

 for new media, and with new apparatuses 

 adapted to them. 



If Mr. Spencer wishes to cast any 

 fresh light upon those factors of organic 

 evolution respecting which he now con- 

 fesses that Darwin's language and his 



1 As in the nudibranchiate mollusca. 



