handle themselves with ease."

"By the same reasoning then, I suppose the intelligent beings, or what
we call men, will be great giants twenty-five feet high?" I put in.

"Some have thought so, but I do not at all agree with them," replied the
doctor. "I stick to the theory of small men for small planets, and large
men for large planets. There is no possible reason for a large man on
Mars, where muscular development is uncalled for and useless, and where
the inhabitable space is small. If there are men on Jupiter, they must
of necessity be enormously strong to hold themselves up and resist
gravitation. If they walk upright (which I think unlikely), their legs
must be very large and as solid as iron. The Martian legs are likely to
be small and puny, and I believe the upper limbs will be much more
strongly developed. In fact, on Mars the Creator had His one great
opportunity of making a _flying man_, and I do not think He has
overlooked it. With a rather small, tightly-knit frame, and the upper
limbs developed into wings as long as the body, flying against the weak
Martian gravitation would be perfectly easy, and a vast advantage over
walking."

"Ah! then perhaps they will fly out to meet you!" I ejaculated.

"If they do, they will be stricken with fear to see that we fly without
wings and so much more rapidly," he answered, and continued: "If a
flying race has been created there, we shall probably find the
atmosphere deeper and relatively (though not actually) denser than the
Earth's. This would serve to add buoyancy and still further diminish
weight, thus making flying quite natural and simple. I certainly do not
believe that the Martians are subjected to the tedium of walking. If
they do not fly, they will at least make long, swift, graceful hops or
jumps of some ten or fifteen feet each. This would require a more hinged
development of the lower limbs, like a bird's. It is also possible that
the lower limbs may have the prehensile function, and do all the
handling and working."

"But how about intelligence and intellectual development? That is the
main thing, after all," said I.

"To answer that takes one into the realm of pure speculation. There are
but few facts to guide one's guesses. But the trip yonder is worth
making, if only to learn that. I do not incline to the opinion that
their civilization is vastly older and more developed than ours.
Granting the nebular theory of the origin of the universe (which i