in a compressed liquid, collapsed when lifted into a lighter medium, and
which, despite the assumed perpetual darkness of their profound abode,
were adorned with variegated colors and furnished with organs of
phosphorescence whereby they could create for themselves all the light
they needed.

Even the fixed animals of the sea, growing, like plants, fast to the
rocks, are frequently vivid with living light, and there is a splendid
suggestion of nature's powers of adaptation, which may not be entirely
inapplicable to the problems of life on strange planets, in Alexander
Agassiz's statement that species of sea animals, living below the depths
to which sunlight penetrates, "may dwell in total darkness and be
illuminated at times merely by the movements of abyssal fishes through
the forests of phosphorescent alcyonarians."

In attempting to judge the habitability of a planet such as Venus we
must first, as far as possible, generalize the conditions that govern
life and restrict its boundaries.

On the earth we find animated existence confined to the surface of the
crust of the globe, to the lower and denser strata of the atmosphere,
and to the film of water that constitutes the oceans. It does not exist
in the heart of the rocks forming the body of the planet nor in the void
of space surrounding it outside the atmosphere. As the earth condensed
from the original nebula, and cooled and solidified, a certain quantity
of matter remained at its surface in the form of free gases and unstable
compounds, and, within the narrow precincts where these things were,
lying like a thin shell between the huge inert globe of permanently
combined elements below, and the equally unchanging realm of the ether
above, life, a phenomenon depending upon ceaseless changes, combinations