The Cactus the Giant Taper. 



CHAPTEE YII. 



'THE SCREW-PINES. 



astonishing diversity of the productions of na- 

 ture in different climates is so great, that even ex- 

 perienced travellers cannot restrain an exclamation of 

 wonder, when they pass from one part of the world to 

 another, and even from one side to the other of the 

 same continent. This is especially the case with ex- 

 plorers of Senegal, when they have just crossed the 

 desolate wastes of the Sahara. The richest vegetation 

 suddenly succeeds to the most complete sterility, and 

 tall, black Africans are met with in place of the 

 stunted Arabs. The trees preserve a never failing 

 freshness growing young again each season before 



