496 



SCIENCE. 



[N. S. Vol. XIX. No. 482. 



that adaptations equally good but of a dif- 

 ferent kind are found in the stems, in the 

 tissiie systems, in several phases of irrita- 

 bility and in other features all involving 

 considerable changes from the ancestral 

 forms, then the chances that all of these 

 adaptations, involving most or all of the 

 external structures of the plant, could have 

 arisen without regard to the environment 

 become so small as practically to disappear. 

 On the other hand, the development of 

 adaptations in causative touch with the 

 environment, by whatsoever method the 

 modification may be brought about, gives 

 a perfect explanation of such cases of con- 

 comitant adaptations as are here in con- 

 sideration.* 



Adaptation, as the probabilities over- 

 whelmingly indicate, usually develops in 

 touch with the environment. But from the 

 point of view of the ecologist the method 

 of evohition, whether by selection of fluc- 

 tuating variations, by inheritance of indi- 

 vidually acquired characters, by mutations 

 or by some other method yet unknown, is a 

 matter of only incidental and not of essen- 



* These cooperations of many adaptations fit- 

 ting a form to a particular habitat, involving 

 changes in many features simultaneously, seem 

 to me to offer one of the very greatest difficulties 

 to the selection theory of the development of 

 adaptations. On the hypothesis of selection of 

 fluctuating variations, favorable variations in one 

 feature bear no relation to favorable variations 

 in another, except in rare cases of correlation. 

 When, therefore, selection is preserving the in- 

 dividuals favorably varying in one character, it 

 is surely preserving unfavorable variations in 

 some other characters. Selection, it would seem, 

 could only produce adaptive modifications in one 

 or a very few characters at a time, and hence 

 simultaneous modifications in many distinct char- 

 acters, such as actually appear to have occurred 

 in such cases as epiphytes, would not be possible. 

 The mutation ^theory oft'ers even greater diffi- 

 culties. Tlie Lamarckian ( Neo-Lamarckian ) 

 theory, on the other hand, admits of indefinitely 

 numerous concomitant or simultaneous adapta- 

 tions, though this theory has its difficulties from 

 other points of view. 



tial interest. On the other hand, it is alto- 

 gether likely that adaptation, pi'.operly 

 studied, will throw light upon the method 

 of evolution, for it is probably true that 

 adaptation has been in some measure the 

 guide of evolution; or, to express the sub- 

 ject in another way, adaptation seems to 

 bear to evolution a relation somewhat an- 

 alogous to the relation of a stimulus to its 

 irritable response. 



Principle 3. Adaptation a Race, not an 

 Individual, Process. — Many phenomena in 

 organic nature point to a distinction be- 

 tween the race and the individuals which 

 compose it. The distinction is not meta- 

 physical but physical, though its precise 

 physical basis is uncertain, the race having 

 its basis in the protoplasm, or the part of 

 it, bearing the characters common to all the 

 individuals, and the individual having its 

 basis in its share of the race protoplasm 

 plus the differences which are its own 

 alone. Now as to the relation of adapta- 

 tion to race vs. individual, two views are 

 possible, aside from any theories: (a) 

 adaptation originates and develops in the 

 individuals, and then, by a method un- 

 known, becomes fixed in the race (a corol- 

 lary of which is that the individuals are 

 the leading or important element in or- 

 ganic nature, the race being secondary) ; 

 and (6) adaptation is primarily a race 

 matter, finding its visible expression in the 

 individuals (a corollary of which is that 

 the race is the leading and important ele- 

 ment, the individuals being secondary to 

 it). The former is the popular conception 

 and that of some students, but the avail- 

 able evidence seems to point overwhelm- 

 ingly to the coi'xectness of the second. The 

 phenomena exhibited by the social insects 

 among animals, the regular transmission 

 of both sexes through one sex, and the 

 phenomena of reproduction generally can 

 only be explained on the basis of race 

 adaptation being dominant over individual 



