This harmonizes with the latest opinion as to the facts. In
his article of Weismann in the Contemporary Review for May, 1890,
Mr. Romanes writes: "Professor Weismann has shown that there is
throughout the metazoa a general correlation between the natural
lifetime of individuals composing any given species, and the age at
which they reach maturity or first become capable of procreation."
This, I believe, has been the conclusion generally arrived at by
biologists for some years past.
Lateness, then, in the average age of reproduction appears to be the
principle underlying longevity. There does not appear at first
sight to be much connection between such distinct and apparently
disconnected phenomena as 1, the orderly normal progress of
development; 2, atavism and the resumption of feral characteristics;
3, the more ordinary resemblance inter se of nearer relatives; 4,
the benefit of an occasional cross, and the usual sterility of
hybrids; 5, the unconsciousness with which alike bodily development
and ordinary physiological functions proceed, so long as they are
normal; 6, the ordinary non-inheritance, but occasional inheritance
of mutilations; 7, the fact that puberty indicates the approach of
maturity; 8, the phenomena of middle life and old age; 9, the
principle underlying longevity.
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