No. 626] 



ADAPTATION 



195 



arrives, I think that most biologists will continue to re- 

 gard the origin of adaptive characters in animals and 

 plants as offering a real and important ])roblem for 

 solution. 



Again, Parker,- while going to no such lengths as this 

 in denying the significance of organic adai)tation, ex- 

 presses his belief that 



range for possible reactions, and of a number of responses that mi<rht 

 be made to ii given set of conditions, one may be quite as appropriate 



seems to be a more truthful description of actual conditions in animal 



It may be freely granted that much iimcimity has been 

 displayed in discovering ada])t:iti()iis which ])r()])ably do 

 not exist. And it is doubtless ti'uc thnt iii;iiiy organisms 

 may live indifferent Iv under a wide r;ni.uv ..f conditions, 

 or may cat indinVrciitly n wi.h" niimv of fo.)ds. \\u\ is 

 not thi> (M.iiditioii of Nrr>^atilit> it-Ml a I'act of a<la|.ta- 

 tion ? The "coiit iinicd adjustincnt of internal relations 

 to external relations" implies that the external relations 

 change. Man, it is true, may live indifferently on the 

 ecjuator or within the Arctic circle. But would any one 

 maintain that the physiological states which adapted him 

 to these unlike conditions did not differ widely in the two 

 localities ? I may make a meal equally well of meat or 

 of vegetables. But the digestive fluids secreted for the 

 occasion would differ in the two cases. 



Again, because two wholly unlike plants grow >id»' !>>' 

 side in the same soil, it does not follow thai tlicy arc ad- 

 justed in (|uite diverse ways to the sanir >rt m rntnlilloNs. 

 The (Mivironm.-nt of an or-'aiiisni d<.ul>tlfss comprises 



