18 THE SUNKEN ISLAND OF ATLANTIS, 
by wind and svaves always remain more or less strangers, or rather 
curiosities, which never mix properly with the natives of the soil, and 
show by their very look that they are intruders. 
If therefore tlie plants of the lignite are to be considered natives of 
the great western continent, we must reject their importation by wind 
and waves, or migratory birds and other animals, unless we are pre- 
pared to grant for their migration an enormous lapse of time and cir- 
cumstances of an extraordinarily favourable nature. Experiments made 
for this purpose with seeds, testing their power to retain vitality and 
extend their geographical range, have shown that these means are quite 
insufficient to explain the distribution of plants over our globe.* 
But there is another means of intercommunication, that of gradual 
migration, which, though slow, is always in steady progression, and 
the only mode which plants at all times must have adopted to find 
their way from the centre of their creation to the limits of their dis- 
tribution, i, e. spreading as far as the nature of the soil and the climate 
was favourable to the progress of the individuals. Eivers, mountain- 
ranges, great lakes, etc., oppose an extension of this kind, but these 
difficulties are generally such as time and the changes wrought by it 
wUl overcome. Great oceans only place an insurmountable barrier to 
tlris gradual migration. 
All these considerations force us to the conclusion thai there must 
have been a continental connection. In tJie Tertiary period^ or at 
the time when lignite was formed^ Europe mud have been connected 
with North America, and the Atlantic Ocean must have been divided at 
one place or other hy a continent. This conclusion, founded upon 
strictly scientific reasoning, would become more certain if it were pos- 
sible to furnish positive proof that a continent, as a connecting link 
between the two worlds, really existed, or if we could trace the outline 
T 
of this central continent. In attempting this by no means easy task, 
• from foreign sources, would seem opposed to this conclusion, but it should be 
. rcmeiabered that man was the principal agent who effected the change in those 
islands. — En. 
* From the experiments made bj Danvin, Eerkeley, Salter, Alph. de Can- 
dolle, and Murtius, it is clear how insignificant is the part played by the sea 
and its waves as an agent in the distribution of plants. Of 98 species, the 
seeds of which were experimentalized upon, only 19 retained their germinating 
power after being six wects submerged in sea-water, and only 7 after three 
iiiuuths. The rest either became rotten or sank in the water, and could 
therefore not have reached a distant shore. (Bibl. Univers. de QTen^ve, 1858, 
i. pp. 89-1)2 ; Neuc Jnhrbuch. fiir Min. 1858, p. 877.) 
