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changes. These ontogenetic changes may so exactly correspond 
and synchronize with the ontogenetic changes of the parent 
that there may be no Variation between parent and offspring at 
the same age. 
I fear that in many cases ontogenetic changes are confound- 
ed with Variations—the differences due to inequality of age not 
being properly considered. The unlikeness between non-coeval 
individuals is often due to their not being in the same 
stage of ontogeny. Differences between coeval individuals of 
different parents might be due to a slight disproportion in 
relative development from a phylogenetic point of view (negroes 
and Caucasian, agricultural labourers and peers); and such 
differences might be termed phyletic unlikeness.* This avoids 
any argument as to whether the parents belong to different 
species, sub-species, or incipient species in any cases. 
Between different offspring of the same parents, between 
different members of the same litter, there are differences: 
1.—Sexual, as between the two sexes. 
2.—Individual, as between members of the same sex. 
Differences from the same-sexed parent at the same age would 
be Variation as I wish to define it. 
Changes in the plumage of birds in connection with the 
breeding-time, as in the Ruff, are sometimes called Variations ; 
but if such changes are inherent in all individuals of the species, 
they are not Variations, even if the term were used in its 
widest sense. They may be called “ genital changes.” 
*In a field of daisies it may be noticed that in some flowers the petals are 
much more strongly tinged with pink than in others, in some cases the younger 
flowers are more pink than the older, in some cases the petals are scarcely 
tinged at any age. These are not variations, even if the term were used to 
indicate departure from a normal type ; because it would be impossible to indicate 
the normal type. The fact is that the differences are, in part, ontogenetic as 
regards different-aged flowers of the same plant, and, in part, phyletic unlikeness 
as regards different plants. The daisy is probably retrograding from an entomo- 
philous to a more complete anemophilous condition—the red petals being the 
remains of a more perfect entomophilous stage—the “ phyletic unlikeness”’ indi- 
cating differing degrees of retrogression. 
