the northern hemisphere all the way to the ``Cross'' in the southern.
Similar lanes are found in many other clusters, and they are generally
associated with flanking rows of stars, resembling in their
arrangement the thick-set houses and villas along the roadways that
traverse the approaches to a great city.

But to return to the black gaps. Are they really windows in the
star-walls of the universe? Some of them look rather as if they had
been made by a shell fired through a luminous target, allowing the eye
to range through the hole into the void space beyond. If science is
discretely silent about these things, what can the more venturesome
and less responsible imagination suggest? Would a huge ``runaway
sun,'' like Arcturus, for instance, make such an opening if it should
pass like a projectile through the Milky Way? It is at least a
stimulating inquiry. Being probably many thousands of times more
massive than the galactic stars, such a stellar missile would not be
stopped by them, though its direction of flight might be altered. It
would drag the small stars lying close to its course out of their
spheres, but the ultimate tendency of its attraction would be to sweep
them round in its wake, thus producing rather a star-swarm than a
vacancy. Those that were very close to it might be swept away in its
rush and become its satellites, careering away with it in its flight
into outer space; but those that were farther off, and they would, of
course, greatly outnumber the nearer ones, would tend inward from all
sides toward the line of flight, as dust and leaves collect behind a
speeding motor (though the forces operating would be different), and
would fill up the hole, if hole it were. A swarm thus collected should
be rounded in outline and bordered with a relatively barren ring from
which the stars had been ``sucked'' away. In a general sense the M8
cluster answers to this description, but even if we undertook to