308 THE REASON WHY. 



"Blessed is the man that walketh not in the counsel of the ungodly, nor 

 standeth in the way of sinners, nor sitteth in the seat of the scornful : " 



operated in promoting the diffusion of floral tribes. Vegetation occurs over tha 

 whole globe, therefore, under the most opposite conditions. Plants flourish in 

 the bosom of the ocean as well as on land, under the extremes of cold and heat 

 in polar and equatorial regions, on the hardest rocks and the soft alluvium uf 

 the plains, amidst the perpetual snow of lofty mountains, and in springs at tho 

 temperature of boiling water, in situations never penetrated by the solar rays, 

 as the dark vaults of caverns, and the walls of mines, as well as freely exposed. 

 to the influences of light and air. But these diverse circumstances hav 

 different species and genera. There is only one state which seems fatal to tho 

 existence of vegetable life the entire absence of humidity. 



1209. By species we understand so many individuals as intimately resemble 

 each other in appearance and properties, and agree in all their permanent 

 characters, which are founded in the immutable Laws of creation. An 

 established species may frequently exhibit new varieties, depending upon local 

 and accidental causes, but these are imperfectly, or for a limited time, if at all, 

 perpetuated. 



1210. A genus comprises one or mere species similar to each other, but 

 essentially differing in formation, nature, and in many adventitious qualities 

 from other plants. A tribe, family, group, or order, comprises several genera. 



1211. The known number of species in the vegetable kingdom has been 

 gradually enlarged by the progress of maritime and inland discovery; bufc 

 owing to great districts of the globe not having yet been explored by the 

 botanist, the interior of Africa, and Australia, with sections of Amerif-a, Asia. 

 and Oceanica, it is impossible to state the exact amount. The successive 

 augmentation of the catalogue appears from the numbers below : 



Species. 



Theophrastua 500 



Pliny 1,000 



Greek, Roman, and Arabian botanists . . 1,400 



Bauhin 6,000 



Linnaeus 8,800 



Persoon 27,000 



Humboldt and Brown 38,000 



DeCandolle .... ., ',. *. '. ; . '. . 66,000 



Lindley . . . . . . . . . 86,000 



Hinds. . . ...... . . . 89,000 



1212. Vegetable forms are divided into three great classes which diiTer 

 materially in their structure:!. Cryptogamous plants those which have 

 no flowers, properly so called, mosses, lichens, fungi, and ferns : as distinguished 

 from those which are phaenogamous, or flower-bearing, to which the two 

 following classes belong. 2. Endogenous plants, which have stems increasing 

 from within, also called Monocotyledons, from having only one seed-lobe, as tho 

 numerous grasses, lilies, and the palm family. 3. Exogenous plants, which 

 have stems growing by additions from without, also called Dicoteledons, from 

 the seed consisting of two lobes, the most perfect, beautiful, and numerous 

 class, embracing the forest trees, and most flowering shrubs and herds. 



1213. The exogens furnish examples of gigantic size, and great longevity. In 

 South America on the banks of the Atabapo, Humboldt measured a Bombax 

 eaiba more than 120 feet high, and 15 in diaunetor ; and near Cumana, he found 



