LAWS OF GROWTH NOT DISCUSSED. 189 
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.t 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 
(that ts, 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. Fora 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. 
t Proceedings of the American Association, vol. XXxII, pp 352-361. 
