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Again, the Lachen valley at this spot is nearly equi-distant from the tropical forests of the Terai and the sterile mountains of Tibet, for which reason representatives both of the dry central Asiatic and Siberian, and of the humid Malayan floras meet there.
Each hill is a miniature Orizaba, so far as it rises, and hundreds of abrupt hills collected in a space comparatively so limited so dovetail the floras of different levels as in a degree to cause them to coalesce and effect a certain mutual adaptation of habits. Good neighborhood has established itself rather more completely among the vegetable than with the human part of the inhabitants.
De Candolle has well remarked in his great and admirable work, that floras gain by naturalisation, proportionally with the number of the native genera and species, far more in new genera than in new species. To give a single instance: in the last edition of Dr. Asa Gray's 'Manual of the Flora of the Northern United States, 260 naturalised plants are enumerated, and these belong to 162 genera.
The term variety, again, in comparison with mere individual differences, is also applied arbitrarily, for convenience sake. Guided by theoretical considerations, I thought that some interesting results might be obtained in regard to the nature and relations of the species which vary most, by tabulating all the varieties in several well-worked floras. At first this seemed a simple task; but Mr.
There would be extremely few shells in the beds thus formed, the southern and northern divisions of which would present two very different floras and faunas, and would in all probability be referred by future geologists to widely different epochs.
Wherever the Carboniferous deposits have been traced, in the United States, in Canada, in England, France, Belgium, Germany, in New Holland, at the Cape of Good Hope, and in South America, the general aspect of the vegetation has been found to be the same, though characterized in the different localities by specific differences of the same nature as those by which the various floras are distinguished now in different parts of the same zone.
De Candolle has well remarked in his great and admirable work, that floras gain by naturalisation, proportionally with the number of the native genera and species, far more in new genera than in new species. To give a single instance: in the last edition of Dr. Asa Gray's 'Manual of the Flora of the Northern United States, 260 naturalised plants are enumerated, and these belong to 162 genera.
Whence came that primordial organism whose transmuted descendants make up the existing faunas and floras of the globe? There was a time, soon after the doctrine of evolution gained a hearing, when the answer to that question seemed to some scientists of authority to have been given by experiment.
At the extremities of the Great Central Plain, the Sierra and Coast Ranges curve around and lock together in a labyrinth of mountains and valleys, throughout which their floras are mingled, making at the north, with its temperate climate and copious rainfall, a perfect paradise for bees, though, strange to say, scarcely a single regular bee-ranch has yet been established in it.
The remarkable facts in regard to the Eastern American and Asiatic floras which these speculations were to explain have since increased in number, especially through the admirable collections of Dr. Maximowicz in Japan and adjacent countries, and the critical comparisons he has made and is still engaged upon.
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