" He urges, that these
constant differences cannot be attributed to natural selection, because
they occur in different valleys on the same side of the mountain, where
food, climate, and enemies are the same; and also, because there is no
greater difference in passing from the rainy to the dry side of the
mountains than in passing from one valley to another on the same side
an equal distance apart. In a very lengthy paper, presented to the
Linnean Society last year, on "Divergent Evolution through Cumulative
Segregation," Mr. Gulick endeavours to work out his views into a
complete theory, the main point of which may perhaps be indicated by the
following passage: "No two portions of a species possess exactly the
same average character, and the initial differences are for ever
reacting on the environment and on each other in such a way as to ensure
increasing divergence in each successive generation as long as the
individuals of the two groups are kept from intercrossing."[49]
It need hardly be said that the views of Mr. Darwin and myself are
inconsistent with the notion that, if the environment were absolutely
similar for the two isolated portions of the species, any such necessary
and constant divergence would take place.
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