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1878.] Relation of Animal Motion to Animal Evolution. 47 
LY, 
It has been maintained above, that environment governs the 
movements of animals, and that the movements of animals then 
alter their environment. It has also been maintained that the 
movements of animals have modified their structure so as to 
render them more or less independent of their environment. 
The history of animal life, is in fact that of a succession of con- 
quests over the restraints imposed by physical surroundings. Man 
has attained to a wonderful degree of emancipation from the iron 
bonds that confine the lower organisms. 
It becomes then all important to examine into the elements in- 
volved in animal movements. 
These are of the two classes, reflex and conscious. To the 
former, belongs the accelerated activity of muscular action and 
circulation, inferred to have accompanied increase in the percent- 
age of oxygen in the atmosphere, during the earlier periods of 
geological time. To the consciously performed acts belong all 
those due to states of pain or pleasure in animals; such as are 
excited by the four classes of stimuli already mentioned. 
Doubtless physical changes in the surrounding medium have 
always produced new reflex movements in animals, and have been 
a first element in evolution. Such has been the immediate cause 
= of change of structure in plants, and in animals so far as they are 
unconscious. But consciousness brings with it limitless possibili- 
= ties, since it places an animal in contact with innumerable stimuli, 
which leave unconscious beings unaffected. All the causes which 
provoke the movements of higher animals are appeals to con- 
‘sciousness, and the consequences due to movements of such 
beings have only been possible through consciousness. 
It is evident then that sensibility to impressions has been the 
prime essential to the acquisition of new movements, and hence 
of new structure, other things being equal. Another essential, 
not less important, has been memory ; because without this fac- 
ulty, experience, and hence education and the acquisition of habits. 
_ of movement, are not possible. 
The ascending development of the bodily structure in higher 
animals has thus been, in all probability, a concomitant of the 
evolution of mind, and the progress of the one has been depend- 
= ent in an alternating way on the progress of the other. The de- 
velopment of mind has secured to animals the greatest degree of 
independence of their environment of which they are capable. — 
R 
