176 



verted into a ^ if-mold. The deeper roots of the 



trees penetrate to. and draw a portion of their inorganic food 

 ''■ ■ ''>' - "'wer sti-ata of sand, and mnch of this is returned to 

 - "he dead leaves, thus restoring to the upper layei-s 



of the sand some of the food matter leached out by yeai-s of 



TABLE XI. CLEABI56 DT BLACK-.JACK ASSOCIATION. 



other species : Teuerium eanadeiue. Eu- 

 phorbia eorollata. 



TABLE Xn. 5ATCBAL 0PE5T«<G 15 BLACK-JACK 

 ASSOC IATI05. 



Other species : Callirrhoe trio.ngulata. Ca- 

 rex fjra'cida. 



* See p. lo'-*. 



