April 23, 1897.] 



SCIENCE. 



635 



cation, there will be a gradual and cumula- 

 tive development of coincident variations 

 under the action of natural selection. The 

 adaptive modification acts, in short, as a 

 screen to perpetuate and develop congenital 

 variations and correlated groups of these. 

 Time is thus given to the species to develop 

 by coincident variation characters indis- 

 tinguishable from those which were due to 

 acquired modification, and the evolution of 

 the race will proceed in the lines marked 

 out by private and individual adaptations. 

 It will appear as if the modifications were 

 directly inherited, whereas in reality they 

 have acted as the fostering nurses of con- 

 genital variations. 



It follows also that the likelihood of the 

 occurrence of coincident variations will be 

 greatly increased with each generation, 

 under this ' screening ' influence of modi- 

 fication; for the mean of the congenital 

 variations will be shifted in the direction 

 of the adaptive modification, seeing that 

 under the operation of natural selection 

 upon each preceding generation variations 

 which are not coincident tend to be elimi- 

 nated.* 



Furthermore, it has recently been shown 

 that, independently of physical heredity, 

 there is among the animals a process by 

 which there is secured a continuity of social 

 environment, so that those organisms which 

 are born into a social community, such as 

 the animal family, accommodate themselves 

 to the ways and habits of that community. 

 Professor Lloyd Morgan, f following Weis- 

 mann and Hudson, has employed the term 

 ' tradition ' for the handing on of that 

 which has been acquired by preceding gen- 

 erations ; and I have used the phrase 

 ' social heredity ' for the accommodation of 



*This aspect of the subject has been especially 

 emphasized in my own exposition, American Natu- 

 ralist, June, 1896, pp. 147 ff. 



t Introduction to Com p. Psych., pp. 170, 210, 

 ' Habit and Instinct, ' pp. 183, 342. 



the individuals of each generation to the 

 social environment, whereby the continuity 

 of tradition is secured. * 



It appears desirable that some definite 

 scheme of terminology should be suggested 

 to facilitate the discussion of these prob- 

 lems of organic and mental evolution ; and 

 I therefore venture to submit the follow- 

 ing : 



1. Variation: to be restricted to ' blasto- 

 genic ' or congenital variation. 



2. Accoimnodation : functional adaptation 

 of the individual organism to its environ- 

 ment. This term is widely used in this 

 sense by psychologists, and in an analogous 

 sense by physiologists. f 



3. Modification (Lloyd Morgan): change 

 of structure or function due to accommoda- 

 tion. To embrace ' ontogenic variations ' 

 (Osborn), i. e., changes arising from all 

 causes during ontogeny. 



4. Coincident Variations (Lloyd Morgan): 

 variations which coincide with or are sim- 

 ilar in direction to modifications. 



5. Organic Selection (Baldwin): the per- 

 petuation and development of (congenital) 

 coincident variations in consequence of ac- 

 commodation. 



6. Orthoplasy (Baldwin): the directive or 

 determining influence of organic selection 

 in evolution. J 



7. Orthoplastic Influences (Baldwin): ail 

 agencies of accommodation (e. g., organic 

 plasticity, imitation, intelligence, etc.),con- 



* ' Mental Development in the Child and the Eace,' 

 Isted., January, 1895, p. 364, Science, August 23, 

 1895. 



t Professor Osborn suggests that ' individual adap- 

 tation' suffices for this; but that phrase does not mark 

 well the distinction between ' accommodation ' and 

 'modification.' Adaptation is used currently in a 

 loose general sense. 



i Elmer's ' orthogenesis ' might be adopted were 

 it possible to free it from association with his hy- 

 potheses of ' orthogenic ' or ' determinate ' variation 

 and use-inheritance. The view which I wish to 

 characterize is in some degree a substitute for these 

 hypotheses. 



