II THE TERM ' ADAPTATION' 33 



(herein lies the importance of use and disuse) ; (3) the 

 struggle for existence, which will indirectly have a different 

 effect according to the difference of the external conditions ; 

 (4) the sudden appearance of new formations through correla- 

 tion (evolution ^er saltum) ; (5) the principle that an organism 

 continually exposed to the same conditions, under the un- 

 interrupted action of the same influences, will after many 

 generations, in consequence of '' constitutional impregnation " 

 (" conservative adaptation "), become different in structure, 

 and have a different relation to the external world than 

 before ; (6) sexual mixing, which may, without any in- 

 fluence of adaptation, lead to the formation of quite new 

 material combinations, that is, to the production of new 

 forms. 



The expression adaptation is often misapplied. Frequently it is 

 erroneously used in an active sense ; people speak of acla2:)tation 

 as of a spontaneously acting power, and in cases in which there can 

 be no question of the use of a character either for the organism which 

 possesses it or for the external world. Adaptation is, however, always 

 something which has been brought about — indeed, iinphes a character 

 which is in some way useful to the organism which possesses it in 

 relation to the external world, or which is necessary or useful to 

 other creatures or to the generality of things. The first is a special 

 adaptation, the last can be called general (cosmic). In the latter 

 sense, of course, ultimately everything is adapted, and we ought, as 

 will be done in the following pages, only to speak of adaptation 

 without the expressed qualification " general " when special adaptation 

 is meant. 



On the other hand, I cannot agree to the limitation of the Darwinian 

 idea of adaptation which Weismann makes, when he will only recognise 

 it as applied to characters gained in the life of the species, not to those 

 gained in the life of the individual. Individuals during their life al.^o 

 adapt themselves to the external world — consider only the variety of 

 the experience which individual animals during life, according to their 

 surroundings and their intelligence, meet with and benefit by, or the 

 special strength of body or any other useful qualities which they 

 acquire in consequence of the external demands upon them. There is 

 a personal adaptation in the Darwinian sense, for Darwin has recog- 



D 



