, 1877-09-09

oAULT, it seems, cannot describe it fairly il
ten pages of big review
REINFORCING THE EV0LUT10N1STs.
The address of Prof. ALLEN THOMPSON nj
Plymouth before the British Association fo1
the Advancement of Science on the snbject
of Embryo1ogy is receiving wide attention on
both sides Of the Atlantic. The Evolution
lists are delighted II consider it impossi-
Bile, says Prof. THOMPSON, for any one to
hayo been faithful student of embryology
i without at the.same time becoming an cyo-
lutionist." The facts advanced by him, as
well as the inforences drawn from them,
furnish abundant support for the Evolution
theory, and serve 10 explain why it has made
such rapid strides. Scarcely generation
ago the doctrine was held in disrepute.
Merely to al1nde to it with respect
was to invite the suspicion Of ortho-
| dox people. Even within ten years learned
divines have spoken contemptuousy Of the
Development hypothesis rs all invention of
- lntdels." Young men who have espoused
it have been made the subjects of re1non-
| strances and prayers, aud old men have been
held up to contunely and reproach as cor
ruptors Of the youth. All this is now
changed. No man with any pretensions to
/ learning now treats the Development hypoth-
| csis IN tho frivolous manner once so CON-
| mon. Those who reject it do SO in eau
tlous and dignifed way, and its ablest oppo-
nents are found in the ranks of those who
! accept parts of it as incontrovertible, in
order the better to demolish the remainder
Christianity is adapting itself to the Evolu-
tion theory much es it did to the Copcrnican
theory; and the defenders of the faith once
delivered to the saints are surprised to find
that no perceptible shock has been caused by
the concessions thus far made
Prof THOMPSON touches lightly on the
variation of species and the much-yexed
question of spontaneous generation. In re-
spect to the latter subject, he is found, as
might be expected, on the side of Prof.
HUXLEY and the ablest biologists of the day
III denying the existence Of any evidence in
its favor. It will be observed that neither
Prof. THOMPSON nor Prof HUXLEY denies
the possibility Of spontaneous generation.
They merely assert thnt not shadow Of
evidence has jet been adduced in its favor
Their position with reference to this contro-
versy is high testi bny to their candor; for,
as the London AthenBuns remarks, spou-
taneous generation is precisely tho one thing
which the eyolutionist wants to complete his
system.
Prof. THOMPSON dwells at some length on
the origin of the lower forms of life, and
then considers the Development of new
beings in the cher groups of the organic
world. He explains, as a typical example,
how IN ordinary Towering plant is produced.
We are indebted to the London dthen9una
for condesation of his remarks.
To effect reproduction it is generally necessary
that two distinct kinds OF structural clements or
cdlis, should be brought into contact In the cen
trail organ, pistit, OF common flower, there ia
cavity containing ornles, within which are little
masses Of protoplasm. primitive organic mat
ter. In another organ, the SfanleH. either In
the SANG or in different flower, there ia
development Of that fine yellow dust called
pollen. When this dust falls upon the sticky sur
face Of the stigma tho little grains Of pollen ecnd
out minute tubes which pass downwards and ulti-
lnatcly reach the ovu1c; they then enter through
tiny aperture, and thus find their way to tho in
closed etnJryo- sac, when minute portion of the
substance contained IN the pol1en-tubes enters the
eac and by its fcrtilizins power sets W in the ger
mnal vesicle that scrtcs Of changes which results
in the formation Of the embryo or infant plant.
Neither the pollen nor The ger'nina rcsiclc can by
itself develop into plant; but when they arc
hronsht together under favorable conditions, the |
result is the production OF new Individual. And |
the same law requiring tic union Of two distinct
elements rules among most members OF the
vegetable kingdom.
The next step in the study of Embryology
is the consideration of the development of
auin1al life. Some. Of the lower forms of
animals have been grouped by nat1lralists
Under the head of Pt0tozod. With the excep-
ton Of these, nil ANIMALS take their origin
from an egg The egg is divided into three,
or four, distinct parts: tho cell-wall, or
she'll; the yelk, or ulellus; the ger7ninal
cesicle and the nncleo}us. The last is not
always visible even under tho most powerful
microscope. Every egg is, in the language
Of embryology, cell. The average diane
Ter of the egg in mammals is notlnore than tho
one hundred and fftieth part of M inch, whilo
It's weight is m inconsidcrable fraction of q
3rain The whole mammalian series, ran nging
rom the mouse to the elephant and includ-
ng man, is developed from eggs of this
description. The yelz Of fowls egg is
'qual in bulk to about 8, ,000, 900 mammalian
'ggs.
Having traced separately the development
# vegetable and of animal life, lit remains
or the student to discover the relations
xisting between the lowest forms of each.
t has been found that they pass into each
'ther by gradations almost imperceptible, so
hat there arc forms of life which uaturalists
AVE been puzzled to call either animal
r vegetable. Until recently it was
imposed that the distinction between the
no great groups of vertebrate and inverte- I
rate animals was more clearly marked than
hat between animals and vegetables in the
owest forms; but Russian naturalist, some