LAWS OF GROWTH NOT DISCUSSED. 1 89 



Assimilational, stimulational, suetudinal, and emotional transfor- 

 mation belong to a class of factors producing what are known as ac- 

 quired characters.* 



Selectional, eliminational, amalgamational, and fecundal transfor- 

 mation may be classed as principles of unbalanced propagation. The 

 principles of unbalanced propagation are abundantly established as 

 genuine methods of change in the average inheritable characters of 

 species, not only by experience derived from the domestication of 

 plants and animals, but by observation of similar effects produced by 

 natural processes. 



3. Principles of Vital Action not here Discussed. 



I have not mentioned "acceleration and retardation" as principles 

 of transformation, for they seem to be but phases of the law of sue- 

 tude ; for, as explained by Cope, use or effort in the parents produces 

 in the offspring accelerated inheritance, while disuse or cessation from 

 effort produces in the offspring retarded inheritance, f So also 

 Hyatt's "Law of Concentration" (or "acceleration," as he often calls 

 it) seems to be a general law of inheritance relating to the transmis- 

 sion of characters originating under any and every principle, the 

 effects, whether progressive or retrogressive, being inherited at earlier 

 and earlier ages in each successive generation. % It is also doubtful 

 whether correlated transformation should be considered a separate 

 principle, for it seems to be simply the inheritance by offspring of 

 characters that have for generations been united in the endowments 



* These four factors are included under what Prof. J. M. Baldwin calls accom- 

 modation (see Nature, April 15, 1897, also '"Development and Evolution," 

 pp. 94 and 151). Accommodation produces three classes of effects: (1) Habitual 

 activity {that is, repeated imitative and intelligent activities, aiding in self-preserva- 

 tion, or in the preservation of offspring or of the communal group); (2) modification 

 (tluit is, acquired physiological and anatomical effects of activity); (3) active (or 

 endonomic) selection determined by the habitual activities of the group in dealing with 

 the environment. For a description of accommodation in lower organisms see 

 Contributions to the Study of the Behavior of Lower Organisms, published by 

 the Carnegie Institution, 1904, where Herbert S. Jennings has shown in a series 

 of elaborate experiments with Amceba, with ciliate infusoria, and with flagel- 

 lates, that their usual method of response to any given stimulus is in accord 

 with what Lloyd Morgan has called "The method of trial and error." This 

 method I would describe as varied tentative action with repeated response till 

 success is gained either by avoiding damage or by attaining advantage. 



t "Origin of the Fittest," pp. 203-207, 228. 



% Proceedings of the American Association, vol. xxxn, pp 352-361. 



