and changes of plants. In zooelogy he was never weary of observing,
especially when he found a strange-looking animal with strange habits.
Spiders, ants, and bees of unknown varieties were brought to light, but
the strangest of his new acquaintances were among the fishy tribes. He
found fish that made long excursions on land, thanks to the wet grass
through which they would wander for miles, thus proving that "a fish out
of water" is not always the best symbol for a man out of his element.
There were fish, too, that burrowed in the earth; but most remarkable at
first sight were the fish that appeared to bring forth their young by
ejecting them from their mouths. If Bruce or Du Chaillu had made such a
statement, remarks Professor Owen, what ridicule would they not have
encountered! But Livingstone was not the man to make a statement of what
he had not ascertained, or to be content until he had found a scientific
explanation of it. He found that in the branchial openings of the fish,
there occur bags or pouches, on the same principle as the pouch of the
opossum, where the young may be lodged for a time for protection or
nourishment, and that when the creatures are discharged through the
mouth into the water, it is only from a temporary cradle where they were
probably enjoying repose, beyond the reach of enemies.

Perhaps the greatest of Livingstone's scientific discoveries during this
journey was that "of a physical condition of the earth's surface in
elevated tracts of the great continent, unknown before." The bogs or
earth-sponges, that from his first acquaintance with them gave him so
much trouble, and at last proved the occasion of his death, were not
only remarkable in themselves, but-interesting as probably explaining
the annual inundations of most of the rivers. Wherever there was a plain
sloping toward a narrow opening in hills or higher ground, there were
the conditions for an African sponge. The vegetation falls down and
rots, and forms a rich black loam, resting often, two or three feet
thick, on a bed of pure river sand. The early rains turn the vegetation
into slush, and fill the, pools. The later rains, finding the pools
already full, run off to the rivers, and form the inundation. The first
rains occur south of the equator when the sun goes vertically over any
spot, and the second or greater rains happen in his course north again.
This, certainly, was the case as observed on the Zambesi and Shire, and
takin