20 Mr. R. B. Hinds on Geographic Botany. 



the isthmus of Panamk; South America, with which are in- 

 cluded the West India islands and the barren Falklands ; Au- 

 stralasia, composed of New Holland, New Zealand, and the Poly- 

 nesian islands. Each division possesses certain characters pecu- 

 liar to itself which distinguish it from the others, and may be con- 

 veniently regarded as a source of comparison. 



No travels of modern date are better known than those of 

 Humboldt and Bonpland in Equinoctial America, and none have 

 been attended with such copious and accurate observations ; 

 though they frequently encountered, especially on elevated sta- 

 tions in the Andes, species of genera common in Europe, yet 

 throughout their whole travels they never saw one exogenous 

 plant which was found equally in the old and new world. Twenty- 

 four species alone were discovered which occurred in the latter, 

 and all these were G7'aminece or Cyperacece. Among 4160 spe- 

 cies met with in New Holland by Dr. Brown, 166 were to be 

 found in Europe ; 15 of these are ExogencB ; 121 belong to Cryp- 

 togamiay being nearly two-thirds of the number ; and 30 to Gra- 

 minecB or Cyperacece. On a portion of the north-west coast exa- 

 mined by Mr. Cunningham he collected 1500 plants, and only 

 52 of these were repeated either in India or South America. 

 Adanson in his * Voyage to the SenegaP mentions, that he only 

 saw two plants in the neighbourhood of that river which he had 

 seen in Europe, tamarisk and purslain. At another river on 

 the same coast, the Congo, of 600 species collected. Dr. Brown 

 has stated that about a twelfth only were met with in South 

 America and India. In high latitudes alone do we find that ex- 

 tensive diffusion which refuses to every restricted spot its own 

 flora. A list of 409 species belonging to Greenland contains 

 only nine peculiar to that country. 



So far then we find little reason to conclude that vegetation 

 originated in one or a few centres, since there is so little identity 

 among plants of different countries. 



4. Had the migration proceeded from a few localities, we 

 should have expected to find, in all situations with similar 

 climates, the identically same species of plants. — That such is 

 not the case is evident from the preceding, but a few moments 

 will be well occupied in showing what does happen here. It is 

 a fundamental principle in geographic botany, that everywhere 

 under similar circumstances similar, but not identical, species 

 exist ; this is a well-known fact, which the daily acquisitions to 

 our knowledge continue to confirm. There is a marked resem- 

 blance In their productions, though the localities under compa- 

 rison may be widely separated; the productions of the Asiatic 

 tropic strongly resemble those of the American ; the temperate 

 extremity of Africa has many points of similarity with the tern- 



