WHERE KNOWLEDGE IS IMPERFECT. 34* 



estimates, large as they seemed, fell immeasurably short of 

 the reality. In attempting to distribute the different species 

 among the then known regions of the globe, Alexander 

 von Humboldt arrived at a total of forty-four thousand 

 species, Phanerogams and Cryptogams included. De Can- 

 dolle extended the estimate to upwards of fifty-six thousand. 



Let us divide, in fancy, the earth into two parts, one which 

 has been visited by travellers, and one which still remains 

 to be explored. Can you determine which would present the 

 larger area ? The latter. 



Thus we possess but a very imperfect knowledge of the 

 luxuriant, the glowing vegetation of the tropical and sub- 

 tropical regions of the New World, in spite of the labours 

 of Bates, Agassiz, Wallace, and others. To the north of the 

 equator, we know very little of the flora of Yucatan, Guatemala, 

 Nicaragua, the isthmus of Panama, the Chaco of Antioquius, 

 the province of Los Pastes. We are not much better ac- 

 quainted with the vegetation of the countries south of the 

 equator. What do we know of the manifold species flourish- 

 ing in Paraguay, in the province of the Missions, in the 

 immense wooded region between the Ucayali, the Rio de 

 la Madeira, and the Tocantin, three affluents of the mighty 

 river Amazon ? We know scarcely anything. 



Our ignorance increases if from America we pass to Africa. 

 Nearly the whole interior of this continent, from 15 N. 

 latitude to 20 S. latitude, is, botanically speaking, a blank 

 to us. The same is the case with the greater portion of 

 Central Asia. The floras of the south and south-east of 



