December 1898] A THHORY OF RETROGRESSION 397 
theories which at present seem to hold the field—for instance, Weis- 
mann’s theory of Germinal Selection, or Mr Francis Galton’s theory 
that so much of an individual is derived from this ancestor, so much 
from that, and so much more from a third. Every one of these latter 
theories ignores what seems to me the patent fact that the characters 
of all the ancestors are not commingled in the final result, the 
adult, but that during ontogeny each parent is represented in turn. 
It is true that watching the development of an individual, we cannot 
say that at such and such a point the great-grandparent ends and 
the grandparent begins, that at this other point the grandparent 
ends, and behold—the parent! The changes are too complex and 
subtle, too swift and fleeting ; moreover, at every turn the variations 
from his ancestry of the individual under observation strike in and 
add to the apparent confusion. 
_ It may be objected that the child during his development does 
not represent exactly, nor even closely, any of his remote ancestors ; 
and this objection would appear fatal to the above theory of heredity. 
On the other hand any sufficient explanation of this vagueness of 
representation will go far to establish, not only this theory, but also 
that theory of retrogression which is the subject of this article, and 
which—if it be a true theory—is in a humble way the complement 
of the theory of evolution. 
Oftspring, as we know, vary from their parents, and if they 
vary, they must do so primarily in one of two ways. Either they 
must revert to the ancestral type, and resemble it more than the 
parent did, or else they must diverge from it still more than did 
the parent. The former variation we term ‘atavistic, the latter we 
may term ‘evolutionary,’ since it is on the lines of these latter varia- 
tions that evolution proceeds. But of so-called atavistic variations, 
_ there are also two kinds; one of which is really atavistic or reversion- 
ary, whereas the other, though apparently atavistic, is actually evolu- 
tionary. True reversion occurs only when the individual varies so 
from his parent that, in his development, he does not recapitulate 
the whole of the life-history of his race, but stops short at a point 
reached by a more or less remote ancestor, whom in this way he 
resembles more than he does his parent. False atavism occurs when 
the individual, at an early stage of his existence, begins by recapitu- 
lating the whole of the life-history of his race up to his parent, but 
during a later stage retraces, or apparently retraces, some of the last 
steps made by himself in his development and by the race in its 
evolution, and thus, by a species of evolutionary variation, resembles 
a more or less remote ancestor more than he does the parent. 
Examples of this false kind of atavism are plentiful in nature. 
The points here set forth are these. First, that development is 
a recapitulation of evolution, in other words, that every individual 
