nimals called Ascidians, which possess a
heart and a circulation, and up to the year 1824 no one would have
dreamt of questioning the propriety of the deduction, that these
creatures have a circulation in one definite and invariable direction;
nor would any one have thought it worth while to verify the point. But
in that year M. von Hasselt, happening to examine a transparent animal
of this class, found to his infinite surprise that after the heart had
beat a certain number of times, it stopped, and then began beating the
opposite way, so as to reverse the course of the current, which returned
by-and-by to its original direction.'--_Huxley's Lay Sermons_, p. 95.

CHAPTER IV.

_HUXLEYISM._

'_A force d'esprit tout lui paroit matiere._'

In one of his interesting 'Lay Sermons,' the most interesting perhaps of
the whole interesting series, Professor Huxley, taking for his theme the
'Physical Basis of Life,' combats 'the widely-spread conception of life
as a something which works through matter, but is independent of it;'
affirming, on the contrary, 'that matter and life are inseparably
connected, and that there is one kind of matter which is common to all
living beings.' The preacher may be safely allowed to have
satisfactorily made out the second portion of this affirmation. With his
own singular felicity of illustration, he shows how all vegetable and
animal tissues, without exception, from that of the brightly coloured
lichen looking so like a mere mineral incrustation on the rock that
bears it, to that of the painter who admires or the botanist who
dissects it, are, however diverse in aspect, essentially one in
composition and structure. He explains how the microscopic fungi
clustering by millions within the body of a single fly, the giant pine
of California towering to the height of a cathedral spire, the Indian
fig-tree covering acres with its profound shadow, the animalcules of
ocean's lowest deep, minute enough to dance in myriads on the point of a
needle, and the Finner whale, hugest of beasts, that disports its ninety
feet of bone and blubber on ocean's billowy heights, the flower that a
girl wears in her hair, and the blood that courses through her veins,
are, each and all, smaller or larger multiples or aggregates of one and
the same structural unit, which, again, is invariably resolvable into
the same identical elements. That unit, he tells us, is an atom or
corpuscle composed of oxygen, nitrogen