294 VIEWS, &CC. PHYSIOGNOMY OF PLANTS. 



Fuego (from 45 to 56 lat.) this uniformity is strikingly mani* 

 fested on the mountains and their declivities no less than in tht 

 plains. How great is the difference of species when we compare 

 the flora of the south of France, in the same latitude as the 

 Chonos Islands off the coast of Chili, with the Scottish flora 

 of Argyleshire, in the parallel of Cape Horn. In the 

 southern hemisphere the same types of vegetation pass 

 through many degrees of latitude. In the regions near the 

 north pole ten flowering plants have been collected on 

 Walden Island (80 J north lat.), while there is scarcely a 

 solitary grass to be met with in the South Shetland Islands, 

 although situated 63 south latitude."* These considera- 

 tions on the distribution of plants prove that the great mass 

 of the still unobserved, uncollected, and undescribed phanero- 

 gamia belong to the tropical zone, and to the contiguous 

 regions extending from twelve to fifteen degrees from it. 



I have deemed it not unimportant to draw attention to 

 the imperfect state of our knowledge in this slightly cul- 

 tivated department of numerical botany, and to treat such 

 questions in a more definite manner than has hitherto been 

 possible. In all conjectures regarding relative numbers, we 

 must first examine the practicability of obtaining the lowest 

 limit; as in the question, of which I have treated elsewhere, 

 regarding the ratio of the gold and silver coined to the 

 quantity of the precious metals existing in a wrought state ; 

 or as in the question of how many stars, from the tenth to 

 the twelfth magnitude, are scattered over the heavens, and 

 how many of the smallest telescopic stars may be contained 

 in the Milky Way?f It is an established fact, that if it 

 were possible to ascertain completely by observation the 

 number of species of the large phanerogamic families, we 

 should at the same time obtain an approximate knowledge of 

 the sum-total of all the phanerogamia on the surface of the 

 earth (that is, the numbers included in every family). The 

 more therefore we are enabled, by the progressive exploration 

 of unknown districts, gradually to determine the number of 

 species belonging to any one great family, the higher will be 

 the gradual rise of the lowest limit, and the nearer we shall 



* Joseph Hooker, Flora Antarctica, pp. 73 75. 

 t Sir John Herschel, Results ofAstron. Obseru. at the Cap of Good 

 Hove, 1847, p. 381. 



