(13) 
The word centrifugal suggests characters developing from 
within rather than as impressed from without: centripetal 
conversely suggests characters impressed upon the individual 
from without, characters which are not the outcome of internal 
causes.* Acquired structural changes have also been spoken 
of as modifications, the term variation being restricted to char- 
acters of germinal origin. 
All the terms suggested for these two classes of characters 
convey something of a definition. Thus the brief convenient 
definition of acquired characters as “those modifications of 
bodily structure or habit which are impressed on the organism 
in the course of individual life” { is obviously suggested more 
or less completely by one set of terms, and “those characters 
or properties with which the individual is originally endowed” § 
by the other set. Another attempted definition of an acquired 
character is as follows :—‘‘ Whenever an organism reacts under 
an external force, that part of the reaction which is directly due 
to the force is an acquired character.” || And although it may 
be impossible entirely to unravel the one part from the other, 
certain elements may easily be discriminated. For instance, 
the starting of the reaction as contrasted with the sequence of 
events which make up the reaction itself is obviously an 
acquired element, and those who maintain the hereditary trans- 
mission of acquired characters are required to prove that a 
reaction which can only be started by an external force in the 
parent, starts without this stimulus in the offspring. 
We owe another definition to Mr. Francis Galton :—“ Char- 
acters are said to be acquired, when they are regularly found 
in those individuals only, who have been subjected to certain 
special and abnormal conditions.” * * 
Professor Lloyd Morgan’s definition conveys nearly the 
same idea :—‘‘ When the complex of stimuli, which constitute 
the normal environment, are sufficiently altered (to upset that 
* “Theories of Heredity,” in the ‘‘ Midland Naturalist,” Nov. 1889. 
+ Prof. J. Mark Baldwin, ‘‘A New Factor in Evolution,” in the 
‘American Naturalist” for July 1896. 
} Professor C. Lloyd Morgan in Baldwin’s “‘ Dictionary of Philosophy 
and Psychology,” New York, 1901, vol. i, p. 10. 
§ E. S. Goodrich, 7. ¢., p. 10. 
| ‘‘ Nature,” vol. li, 1894, p. 55, 
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