DISTRIBUTION OF PLANTS. 
423 
sembles that of places nearer the poles,* we still remark a 
striking resemblance of appearance and physiognomy in the 
vegetation of the most distant countries. This phenomenon 
is one of the most curious in the history of organic forms. 
1 say the history ; for in vain would reason forbid man to 
form hypotheses on the origin of things; he still goes on 
puzzling himself with insoluble problems relating to the 
distribution of beings. 
A gramen of Switzerland grows on the granitic rocks of 
he straits of Magellan."! New Holland contains above 
forty European phanerogamous plants: and the greater 
number of those plants, which are found equally in the 
temperate zones of both hemispheres, are entirely wanting 
m the intermediary or equinoctial region, as well in the 
plains as on the mountains. A downy-leaved violet which 
terminates in some sort the zone of the phanerogamous 
plants at Teneriffe, and which was long thought peculiar 
to that island, 4. is seen three hundred leagues farther north 
near the snowy summit of the Pyrenees. Gramma and 
cyperaceous plants of Germany, Arabia, and Senegal, have 
* The geography of plants comprises not merely an examination of the 
analogies observed in the same hemisphere ; as between the vegetation of 
t.ie Pyrenees and that of the Scandinavian plains ; or between that of the 
Cordilleras of Pern and of the coasts of Chile. It also investigates the 
relations between the alpine plants of both hemispheres. It compares 
the vegetation of the Alleghanies and the Cordilleras of Mexico with 
that of the mountains of Chile and Brazil. Bearing in mind that every 
isothermal line has an alpine branch (as, for instance, that which connects 
Upsala with a point in the Swiss Alps), the great problem of the analogy 
oi vegetable forms may be defined as follows: 1st, examining in each 
hemisphere, and at the level of the coasts, the vegetation on the same 
isothermal line, especially near convex or concave summits ; 2nd, com- 
paring, with respect to the form of plants, on the same isothermal line 
north and south of the equator, the alpine branch with that traced in 
the plains; 3rd, comparing the vegetation on homonymous isothermal 
lines in the two hemispheres, either in the low regions, or in the alpine 
regions. 1 
f Phleum alpinum, examined by Mr. Brown. The investigations of 
this great botanist prove that a certain number of plants are at once 
common to both hemispheres. Potentilla anserina, Prunella vulgaris 
»cirpus mucronatus, and Panicum crus-galli, grow in Germany, in Aus- 
ti’alia, and in Pennsylvania. 
: The Viola cheirantliifolia has been found by MM. Kunth and Von 
uuch among the alpine plants which Jussieu brought from the Pyrenees. 
