XII 
GEOGRAPHICAL DISTRIBUTION OF ORGANISMS 
369 
violent and long-continued gales of wind, we shall not only be 
better able to account for the floras of some of the remotest 
oceanic islands, but shall also find in the fact a sufficient ex¬ 
planation of the wide diffusion of many genera, and even species, 
of arctic and north temperate plants in the southern hemisphere 
or on the summits of tropical mountains. Nearly fifty of the 
flowering plants of Tierra-del-Fuego are found also in North 
America or Europe, but in no intermediate country ; while fifty- 
eight species are common to New Zealand and Northern Europe; 
thirty-eight to Australia, Northern Europe, and Asia; and no 
less than seventy-seven common to New Zealand, Australia, 
and South America. 1 2 On lofty mountains far removed from each 
other, identical or closely allied plants often occur. Thus the 
fine Primula imperialis of a single mountain peak in Java has 
been found (or a closely allied species) in the Himalayas; 
and many other plants of the high mountains of Java, Ceylon, 
and North India are either identical or closely allied forms. So, 
in Africa, some species, found on the summits of the Cameroons 
and Fernando Po in West Africa, are closely allied to species 
in the Abyssinian highlands and in Temperate Europe ; while 
other Abyssinian and Cameroons species have recently been 
found on the mountains of Madagascar. Some peculiar Aus¬ 
tralian forms have been found represented on the summit of 
Kini Balu in Borneo. Again, on the summit of the Organ 
mountains in Brazil there are species allied to those of the 
Andes, but not found in the intervening lowlands. 
No Proof of Recent Lower Temperature in the Tropics. 
Now all these facts, and numerous others of like character, 
were supposed by Mr. Darwin to be due to a lowering of 
temperature during glacial epochs, which allowed these tem¬ 
perate forms to migrate across the intervening tropical low¬ 
lands. But any such change within the epoch of existing species 
is 'almost inconceivable. In the first place, it would necessitate 
the extinction of much of the tropical flora (and with it of the 
insect life), because without such extinction alpine herbaceous 
plants could certainly never spread over tropical forest low- 
1 For fuller particulars, see Sir J. Hooker’s Introduction to Floras of Xew 
Zealand and Australia, and a summary in my Island Life, chaps, xxii. 
xxiii. 
2 B 
