The Roanoke daily times. (Roanoke, Va.) 1895-1897, 1895-12-27
THE SPANS OF LIFE.
DIFFERENCES OF DURATION IN MEN
AND ANIMALS.


Fly and One OF tho Longest the Ele.
phnnt's-Among Insects tho Period OF
Adult Life Varies Greatly.
An essay Of Weismann, charming
and profound and written before the
obsession Of a logical theory had car.
ried him into arid metaphysics, dis.
cussed the duration Of life in men and
animals To many, perhaps to most,
living things, death comes unexpected.
~. with an ironical Indifference to the
period OF tho animals life or to it's bus.
mess of the moment. Tho man may DO
preparing to DO merry; the bird may DO
a-building, the butterfly not yet dry
from the chrysalis, when they are fallen
upon by blind misohance, by enemies
intent only on dinner or by unthinking
microbes Confronted by such extrinsio
accidents, men cry out after thoir kind,
the poet attuning an Intellectual lam
entation, the moralist preaching, the
pagan urging to tho day Of pleasure,
but the naturalist must be dumb. His
opportunity comes with tho animals
that avoid or escape colliding fates, and
that yet after fixed period run down
like clock. The seeds of deaths appar-
emily have been lying inert in the body
and come to fatal maturity after lapse
Of time that varies little among indi-
viduals Of the Same species, but that is
widely different among different kinds
of animals
Threescore and ten is tho natural
period of mans life. The elephant will
1.-Two 200 years, tho horse but half CEN
fury. Singing birds and fowls and pleas.
ants will 1.-Two for nearly 90 years, but
parrots. eagles, falcons and swans arc
known to survive their century. Some
1.-Two through nearly two centuries.
Queen ants and working ants may live
for years. Sir John Lubbock kept a
queen ant alive for 10 years, during all
which period she continued to lay fer
tito eggs, but tho males live only few
days. Queen bees 1.-Two two or thrco
years; workers and drones few months.
although indeed i'll one sense tho death
OF tho latter is unnatural rs the work
ers drive them away from the stores of
food, so that they perish of starvation.
Among insects generally the period of
adult life varies greatly. Many, like
the May flies, dance i'll the sun only for
few hours; tho sexes meet, the eggs
are deposited and the creatures dio be-
fore nightfall. Many butterflies and
moths arc unprovided with feeding or
gans and 1.-Two only Il few hours, others
for many days.
Leaving out of count certain minor
factors, like tho timo required for grow
ing to larger siZo and the slower
growth of animals that must waste time
and energy i'll capturing living food, it
is certain that there is an intimate con-
nectlon all through the animal kingdom
between the duration of life and tho
reproductive habits Animals, in ono
sense. are like the bright and fragrant
flowers of plants; since when their
function is accomplished, when seeds
arc formed, they wither and perish.
The business of the animal seems to be.
not to live its own life, but to reproduce
its own kind, and the term of life at its
disposal is adjusted accurately to the
special difficulties Of this purpose.
Weismann and Alfred Russell Wallace
suggest that death comes as soon as pos
siblo after tho due number of successors
has been produced, in order that each
species may always be represented by
full tale OF young and vigorous indivi-
duals. Natural selection acts like q con-
tractor who has under taken to keep
window box gay with fresh blossoms;
each plant must be removed almost be-
fore its flowers fade.
But our present concern is with tho
fact rather than with explanation of tho
fnaf Nal ftN0, e
as master key, wo find it unlocking
tho secrets of inequalities of life. Tho
May flies 1.-Two only few hours, but
their eggs arc produced abundantly and
have only to be dropped into pools from
which their parents, leaving their chrys-
ais sprang into tho sunny air. Tho
short lived moths and butterflies SINH
larry arc untroubled by family cares
When tho eggs have to be deposited OH
common and abundant food plants tho
females need and possess few hours in
which to accomplish their easy task
Tho males; OH the other hand, hayo to
fly about seeking and sometimes fight
ing for possession of the females, and
to them longer lifo is ,.llottod. But
tcrflics and moths that live for more
eiuH d low uayS afo tHOSo whose cater
pillars require q rarer food plant, q
more carefully chosen nursery and feed
ing ground. Tho females have to fly
about seeking convenient spots for their
offspring. and tho eggs, instead of ripen-
ing and being deposited simultaneous
ly, arc laid from day to day until tho
full tale be- accomplished. In many
tribes of bees tho males play their part
but once, and that during the nuptial
flight of tho uueen. immediately After