40 Relation of Animal Motion to Animal Evolution. [January, 
tufts of grass or weeds that furnished it with a roof, it changes its 
whole shape and builds a bulky, nearly spherical, domed nest. 
Some of its offspring adopt the new style of their parents, but 
others fall back upon their original style. The latter may be con- 
sidered the promptings of a natural innate instinct, but the domed 
nests, the changes initiated by the parents and imitated by the 
more enterprising of their offspring are due to a higher intellect- 
ual power that rejects the blind suggestions of their original 
instinct, and teaches them to follow the paths of experience to 
safety. This is no imaginary case, but rests on facts within my 
own observation. . 
5. 
THE RELATION OF ANIMAL MOTION TO ANIMAL 
EVOLUTION. 
BY E. D. COPE.* 
HE origin of variation in animal structure is, par excellence, 
the object of the doctrine of evolution to explain. There can 
be little doubt that the law of natural selection includes the — 
cause of the preservation of certain modifications of preéxistent 
structure, in preference to others, after they have been brought 
into existence. In what manner or by what process the growing 
tissues of young animals have been so affected as to produce 
some organ or part of an organ which the parent did or does not 
possess, must be explained by a different set of laws. These 
have been termed originative, while those involved in natural | 
selection are restrictive only. 
7 
Of course we naturally look to something in the “surrounding _ : 
circumstances” in which a plant or animal is placed, or its 
“environment,” as the most probable stimulant of change of 
its character, because we know that such beings are totally 
dependent on cosmic and terrestrial forces for their sustenance 
and preservation. The difficulty has been to connect these forces 
with change of structure as originative ; to show their operation 
as multiplying, restricting or destroying organisms already in 
existence is comparatively easy. This difficulty is partially due- $ 
*Abstract of a paper read before the American Association for the Advancement of — 
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