Ancestry of Angiosperms 315 
it at the present time. It is not unreasonable to suppose that both 
phenomena, so similar, may admit of the same explanation. I confess 
it would not surprise me if fresh discoveries in the distribution of 
the Glossopteris flora were to point to the possibility of its also 
having migrated southwards from a centre of origin in the northern 
hemisphere. 
Darwin, however, remained sceptical “about the travelling of 
plants from the north except during the Tertiary period.” But 
he added, “such speculations seem to me hardly scientific, seeing 
how little we know of the old floras.” That in later geological 
times the south has been the grave of the weakened offspring of 
the aggressive north can hardly be doubted. But if we look to 
the Glossopteris flora for the ancestry of Angiosperms during the 
Secondary period, Darwin’s prevision might be justified, though he 
has given us no clue as to how he arrived at it. 
It may be true that technically Darwin was not a botanist. But 
in two pages of the Origin he has given us a masterly explanation 
of “the relationship, with very little identity, between the productions 
of North America and Europe” He showed that this could be 
accounted for by their migration southwards from a common area, 
and he told Wallace that he “doubted much whether the now called 
Palaearctic and Nearctic regions ought to be separated*.” Catkin- 
bearing deciduous trees had long been seen to justify Darwin’s doubt : 
oaks, chestnuts, beeches, hazels, hornbeams, birches, alders, willows 
and poplars are common both to the Old and New World. Newton 
found that the separate regions could not be sustained for birds, and 
he is now usually followed in uniting them as the Holarctic. One feels 
inclined to say in reading the two pages, as Lord Kelvin did to a 
correspondent who asked for some further development of one of 
his papers, It is all there. We have only to apply the principle 
to previous geological ages to understand why the flora of the 
Southern United States preserves a Cretaceous facies. Applying it 
still further we can understand why, when the northern hemisphere 
gradually cooled through the Tertiary period, the plants of the 
Eocene “suggest a comparison of the climate and forests with those 
of the Malay Archipelago and Tropical America‘.” Writing to 
Asa Gray in 1856 with respect to the United States flora, Darwin 
said that “Nothing has surprised me more than the greater generic 
and specific affinity with East Asia than with West America®.” The 
recent discoveries of a Tulip tree and a Sassafras in China afford 
1 Life and Letters, 11. p. 247. % pp. 333, 334. 
3 Life and Letters, 11. p. 230. 
4 Clement Reid, Encycl. Brit. (10th edit.), Vol. xxx1. (“Palaeobotany; Tertiary ”), 
p. 435. 
5 More Letters, 1. p. 434. 
