544 The American Naturalist. [July, 
ments)—but by the reinstatement of it by a discharge of the 
energies of the organism, concentrated as far as may be for 
the excessive stimulation of the organs (muscles, etc.) most 
nearly fitted by former habit to get this stimulation again (in 
which the “ stimulation ” stands for the condition favorable to 
adaptation). After several trials the child (for example) gets 
the adaptation aimed at more and more perfectly, and the 
accompanying excessive and useless movements fall away. 
This is the kind of selection that intelligence does in its 
acquisition of new movements” (ref. 2, p. 179; ref. 6). 
Accordingly, all ontogenetic adaptations are neurogenetic* The 
general law of “ motor excess” is one of overproduction ; from 
movements thus overproduced, adaptations survive; these 
adaptations set the determinate direction of ontogenesis; and 
by their survival the same determination of direction is set in 
phylogenesis also. 
The following quotation from an earlier paper (ref. 7) will 
show some of the bearings of this position: 
“That there is some general principle running through 
all the adaptations of movement which the individual crea- 
ture makes is indicated by the very unity of the organism 
itself. The principle of Habit must be recognized in some 
general way which will allow the organism to do new things 
without utterly undoing what it has already acquired. This 
means that old habits must be substantially preserved in the 
new functions ; that all new. functions must be reached by 
gradual modifications. And we will all go further and say, I 
think, that the only way that these modifications can be got at 
all is through some sort of interaction of the organism with its 
environment. Now, as soon as we ask how the stimulations of 
the environment can produce new adaptive movements, we 
have the answer of Spencer and Bain—an answer directly con- 
firmed, I think, without question, by the study both of the 
child and of the adult—i. e., by the selection of fit movements 
from excessively produced movements, that is, from movement 
variations. So granting this, we now have the further question : 
5 Barring, of course, those violent compelling physical influences under the 
action of which the oe is quite helpless. 
