The Stourbridge Observer, Cradley Heath, Halesowen & District Chronicle.
Stourbridge, West Midlands, England, 1878-03-16 00:00:00

THE ANALOGIES OF PLANT AND
ANIMAL LIFE.

In London, on Monday evening, Mr. Francis Darwin gave
lecture at the London Institution on "The Analogies of
Plant and Animal Life."

The first analogy referred to was that of the seed and
the egg. Both contain a supply of food stored up for
the young, which is gradually exhausted as the young
developes. The carbo-hydrates and nitrogenous ma-
terials in the seed are consumed by the young plant
just as the yolk of the egg is consumed by the hatch-
ing chicken. Both among plants and animals
there are great differences in the degree of develop-
ment attained by the young before they "enter the
world." A calf or lamb soon leads an active
existence, while a young kangaroo is for a long
time merely capable of a passive existeire in its
mother's pouch. So, the lecturer said a tobacco; plant
receives only enough food for its pair of leaves, and
then has to depend on its own exertions for exist-
ence, while a young mangrove remains attached to
the capsule, still hanging on the mother plant for sup-
port till it has taken root. Among animals reproduc-
tion is largely dependent on the fact that the parents
are locomotive, and one sex seeks the other. Among
plants the pollen is practically locomotive, either by
the agency of insects, wind, or other means. The
locomotiveness of the mother animal enables her to
deposit her young or her eggs in suitable places ; among
plants the same result is obtained by the seeds being
locomotive. Very various and sometimes strange are
the means of transport of seeds. Some are capable of
a motion by which they bury themselves in the ground.
Stipa pcnnata (feather glass), for example, has a seed
with a strong point, which twists when the seed is
dried and untwists when wetted, and thus damp nights
and dry days cause it to rotate. As it is barbed, it
gradually bores its way even into hard soil, the barbs
preventing any retrograde movement. .
In considering the analogies between animals and
plants it is not enough, Mr. Darwin says, to merely
compare those functions which are strictly and
physiologically similar in the two kingdoms. Rather
there should be studied the needs which arise either in
a plant or an animal, and he way in which the same
need is supplied in the other kingdom. In the life of
animals the first needs that arise are supplied by
certain instinctive movements and the powers of
growth which exist in young seedlings would cer-
tainly be called instinctive if they existed in
animals. These are the powers of directing the growth
in relation to the force of gravity and in relation to
light. The young roots goes down, the young stem goes
upwards, and the fact is so familiar that we fail to
think it wonderful. Yet we cannot generalize the fact
so far as to say it is the nature of all stems to grow up
and all roots to grow down, for some sterns have a
strong tendency to grow down and some roots have no
wish to grow downwards. There is no structural
reason why a root should grow down. Again, an
animal, needs to be on the alert to changes going on in
the world around it, it needs delicate sense organs to
perceive the approach of enemies or the whereabouts
of its food. In the case of some plants motions occur
which can only be compared to the result of a trans-
mission of stimulus on nerve. The cases of the sun-
dew, the Venus flytrap, and the sensitive plant were
referred to in illustration, and the habitual move-
ments were compared to similar habitual movements
in animals. Just as animals soon disregard noises or
movements to which they get accustomed, so plants,
though at first sensitive, disregard frequently repeated
similar disturbances. The sleep of plants cannot be
compared to that of animals, as they really do work
all the night through. After accounts of many experi-
ments on the sensitiveness of plants, Mr. Darwin con-
cluded by suggesting that, while the plant physiologist
has much to learn from the worker who confines
himself to animals, it is possible that plant physiology
can teach us something of the machinery of our own
lives.