EFFECT OF SETTLEMENT UPON INDIGENOUS VEGETATION. 225 
But with many plants introduced, we can only reason by analogy 
as to the manner of their introduction. In an article on the weeds 
of Europe in the Cornhill Magazine, an anonymous writer states 
that a common English weed was introduced into an Antarctic 
island by the use of a spade which had some mould attached to 
the blade, and the plant has now spread all over the island. 
Darwin gives instances of seeds being found in balls of clay 
attached to the feet of birds, and even to the elytra of beetles. 
Still, the method of introduction of many foreign weeds must in 
the nature of things always remain more or less of a mystery. 
Many aliens have arrived in the colony attached to the wool of 
sheep or the hair of other animals as in the case of the Bathurst 
Burr—a species of vegetable stowaway. | 
As to the methods of spreading, they are various. Cultivation 
of the soil brings the weeds in its wal*e, and they manage to spread 
some how. Some have specially constructed seeds to float through 
the air—anyone who has seen thistle infested country on a windy 
day will have a good idea how thistles spread. The Composites 
are especially rich in plants adopting this contrivance. Others 
stick to the wool and hair of animals by hooks, barbed hairs, or 
sticky glands. Others again have seeds so minute that a high wind 
will carry them, although they are not furnished with special 
apparatus for the purpose. 
Railways and roads are active helpers in the dissemination of 
aliens, especially the former. The land being fenced in is pro- 
tected from the depredations of stock, and thus protected the weeds 
flourish and spread rapidly. In 1887 I remember noticing on the 
Mudgee Railway near Lue that there were miles of the embank- 
ments one tangled mass of Meliotus parviflorus. And in the 
neighbourhood of Bowenfels the railway line enclosures are thickly 
covered with a species of Hypocheris: itis pretty plentiful outside 
but inside the land is a golden sheet of the yellow flowers. Rivers 
also act in the same way, and especially carry weeds when in flood 
and deposit them on the flooded lands. I first noticed Ranunculus 
O—Sept. 7, 1892. 
