March 25, 1904.] 



SCIENCE. 



497 



adaptation. The distinction often made 

 between adaptations for the good of the 

 individual, such as irritable responses to 

 stimuli, and those for the good of the race, 

 such as various reproductive processes, is 

 merely a matter of convenience without 

 logical basis, for not only is the line be- 

 tween the two extremely indefinite, but also 

 it is evidently as necessary for the good of 

 the race to preserve the reproducing indi- 

 viduals as to secure their reproduction. 

 Adaptation may apparently all be reduced 

 to a race basis, only that being individual 

 which is connected with individual vari- 

 ability. The relation of the race to the 

 individual appears to resemble somewhat 

 the relation of the mortality tables to the 

 individual human life; or the race is like 

 a mighty moving current, while the indi- 

 viduals are the ripples that play upon its 

 surface or the eddies that swirl in its 

 depths. In practice, therefore, adaptation 

 is to be studied from the point of view of 

 its advantage to the race under considera- 

 tion rather than from the point of view of 

 its individuals; and, further, conclusions 

 can not safely be dravra. from individual 

 cases, but must be based upon studies of 

 the race, which can be accomplished best 

 through the use of statistical methods. A 

 corollary of this principle is this, that the 

 meaning of adaptation is to be sought 

 deep in the activities of protoplasm rather 

 than in the superficial manifestations of 

 structure. Structure is but the external 

 manifestation of protoplasmic activity, the 

 tool, as it were, by the aid of which the 

 protoplasm more perfectly accomplishes its 

 work. 



Principle 4. Metamorpliic Origin of 

 Adaptation. — In such cases as I can recall, 

 in which the phylogeny of an adaptive 

 feature is known with reasonable certainty, 

 it seems to be the case that the new adapta- 

 tion has not arisen de novo out of the plant 

 substance, but through the metamorphosis 



of some preexistent feature, itself formerly 

 adaptive. It seems to me logically a prob- 

 ability that adaptations frequently, if not 

 generally, have their origins in the meta- 

 morphoses of preexisting adaptations, and 

 omnis adaptatio e adaptations may yet be- 

 come a postulate of ecology. The origin 

 of a new adaptation, upon this principle, 

 would be somewhat after this manner. 

 "When changing environmental conditions, 

 or the opening of a new field, bring about 

 a need for a new adaptation, both change 

 and need arising very gradually, this need 

 can be met, and a new adaptation can arise, 

 only in case there is available in the plant 

 some existent feature which happens to be 

 capable of filling that need in its earliest 

 stages, and of being modified to fill it bet- 

 ter, either by selection of its fluctuating 

 variations or mutations, or by more direct 

 method, as the need becomes more intense. 

 In such a case, when the full intensity of 

 the need has been reached, the modification 

 or metamorphosis of the original feature 

 will have gone so far that we recognize a 

 new adaptation. If, however, no feature 

 capable of filling the need in its earlier 

 stages exists, or if the need arises too sud- 

 denly, then there is no adaptation, the 

 organism can not meet the new conditions 

 confronting it, and it must either keep to 

 its old mode of life, or, if that be impos- 

 sible, become extinct. Such a principle 

 gives a logical explanation of the remark- 

 able irregularity of distribution of adapta- 

 tion at the present day, and removes much 

 of the difficulty as to the origin of new 

 adaptations. In diseiissing the origin of 

 adaptation we too often forget, not only 

 that the need for new adaptations must 

 arise as a rule very gradually, but also that 

 the modifying agency, whatever that may 

 be, makes its effects felt very gradually; 

 or, as it may be expressed, the plant is 

 passed from under the action of one adapt- 

 ing agency to the action of another not 



