usually so powerful in taking possession of the soil.

In Australia another composite plant, called there the Cape-weed
(Cryptostemma calendulaceum), did much damage, and was noticed by Baron
Von Hugel in 1833 as "an unexterminable weed"; but, after forty years'
occupation, it was found to give way to the dense herbage formed by
lucerne and choice grasses.

In Ceylon we are told by Mr. Thwaites, in his _Enumeration of Ceylon
Plants_, that a plant introduced into the island less than fifty years
ago is helping to alter the character of the vegetation up to an
elevation of 3000 feet. This is the Lantana mixta, a verbenaceous plant
introduced from the West Indies, which appears to have found in Ceylon
a soil and climate exactly suited to it. It now covers thousands of
acres with its dense masses of foliage, taking complete possession of
land where cultivation has been neglected or abandoned, preventing the
growth of any other plants, and even destroying small trees, the tops of
which its subscandent stems are able to reach. The fruit of this plant
is so acceptable to frugivorous birds of all kinds that, through their
instrumentality, it is spreading rapidly, to the complete exclusion of
the indigenous vegetation where it becomes established.

_Great Fertility not essential to Rapid Increase_.

The not uncommon circumstance of slow-breeding animals being very
numerous, shows that it is usually the amount of destruction which an
animal or plant is exposed to, not its rapid multiplication, that
determines its numbers in any country. The passenger-pigeon (Ectopistes
migratorius) is, or rather was, excessively abundant in a certain area
in North America, and its enormous migrating flocks darkening the sky
for hours have often been described; yet this bird lays only two eggs.
The fulmar petrel exists in myriads at St. Kilda and other haunts of the
species, yet it lays only one egg. On the other hand the great shrike,
the tree-creeper, the nut-hatch, the nut-cracker, the hoopoe, and many
other birds, lay from four to six or seven eggs, and yet are never
abundant. So in plants, the abundance of a species bears little or no
relation to its seed-producing power. Some of the grasses and sedges,
the wild hyacinth, and many buttercups occur in immense profusion over
extensive areas, although each plant produces comparatively few seeds;
while several species of bell-flowers, gentians, pinks, and mulleins,
and even some of the com