Southwest-sentinel. [volume] (Silver City, N.M.) 1883-189?, 1895-05-21
THE SPANS OF LIFE.
DIFFERENCES OF DURATION IN MEN
AND ANIMALS.

One Of the Shortest II that Of che May
FIy snd Ono Of the Longest the Eis-
phant's-Amons Insects tho Period Of
Adult Lie Varies Greatly.
An essay Of woismann, charming
and profound and written before the
obsession Of a logical theory had car
riod him into arid metaphysics, dis
cusscd the duration Of life in men and
animals To many, perhaps to most,
living things, death comes unexpected
ly, with an ironical indifference to the
period Of the animals life or to its bus.
mess Of the moment The man may be
preparing 10 be merry; the bird may be
a-building. the butterfly not yet dry
from the ohrysalis, when they are fallen
upon by blind mischance, by enemies
intent only on dinner or by unthinking
microbes. Confronted by such extrinsio
accidents, msn cry out after their kind,
the poet attuning an Intellectual lam
entation, the moralist preaching, the
pagan urging to the 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 a fixed period run down
like q clock. Tho 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
live 200 years, the horse but half CEN
tury. Singing birds and fowls and pheas-
ants will live for nearly 20 years, but
parrots. eagles, falcons and swans arc
known to survive their century. Some
live through nearly two centuries.
Queen ants and working ants may live
for years. Sir John Lubbock kept q
queen ant alive for 1S years, during all
which period sho continued to lay fer
tile eggs, but the males live only few
days Queen boes live two or three
years; workers and drones a few months,
although indeed in one sense the death
Of the latter is unnatural, as 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 in the sun only for
q few hours; tho soxes meet, the eggs
are deposited and the creatures die be-
fore nightfalL Many butterflies and
moths are unprovided with feeding or
gans and live only q few hours, others
for many days
Leaving out of count certain minor
factors, like the timo required for grow
ing TO q larger size and tho slower
growth of animals that must waste time
and energy in capturing living food, 10
is certain that there is an intimate con-
neotion all through the animal kingdom
between the duration Of life and the
reproductive habits. Animals, In one
sense, are like the bright and fragrant
flowers Of plants; since when their
function Is accomplished, when seeds
are formed, they wither and perish.
The business Of ths animal seoms 70 be,
not to live its own life. but to reproduce
its own kind, and the term Of life at les
disposal is adjusted accurately TO the
special difficulties Of this purpose.
Weismann and Alfred Russell Wallace
suggest that death comes as soon as pos
sible after tho due number Of Successors
has beon produced, in order that each
species may always be represented by a
full tale Of young end vigorous indivi-
duals Natural selection acts like q con-
tractor who has undertaken to keep a
window box gay with fresh blossoms;
each plant must be removed almost be-
fore its flowers fade.
But our present concern is with the
fact rather than with explanation Of the
fact. Taking the needs Of reproduction
as q master key, we find it unlocking
the secrets Of inequalities of life. Tho
May flies live only a few hours bus
their eggs are produced abundantly and
have only to be dropped into pools from
which their parents, leaving their chrys-
alis, sprang into the sunny air. The
short lived moths and butterflies SINH
larly are untroubled by family cares.
When the eggs have TO be deposited on
common and abundant food plants the
females need and possess few hours In
which TO accomplish their easy task.
The males, on the other hand, have to
hy about seeking and sometimes fight
ing for possession Of tho females, and
to them q longer life is lllottod. But
terilies and moths that live for more
than a few days arc those whose cater
pillars require a rarer food plant, q
more carefully chosen nursery and feed
ing ground The females have to fly
about seeking convenient spots for their
offspring, and the eggs, instead Of ripen-
ing and being deposited simultaneous
ly, are laid from day 10 day until the
full talo bo accomplished In many
tribes Of bees the malos play their part
but once, aud that during the nuptial
flight Of the queen. Immediately after
ward they die or shortly after are killed
by the workors The queens. secluded IN
the middle Of the hive produce crops
OF workers year after year, and so their
lives are prolonged
Among the birds and beasts parental
cares have brought length Of days with
them. The small singing birds are rapid
breeders, sometimes producing i've on
sex nostlinga twice year, but their
enemies are equally numerous, and de-
spite the constant attention of the male
and female play such havoc with the
young that hardly In 30 years win o
paiS rear up young enough 70 maintain
the species. Birds like pheasnnta and
fowls are still moro prolific. but old
aud young like are preyod upon by q mul-
tltude Of enemies. The birds Of prey are