Chap. VI] EDAPHIC INFLUENCES IX THE TROPICS 403 



laeoides i^radually sited their cortex. 

 A\iceiinia (ifficinalis (Figs. 223, 4 ; 

 224), tngethcrwith the two American 

 species, Sonncratia acida and S. 

 alba, Ceriops Candolleana, and the 

 American combretaceous Laguncu- 

 laria racemosa, all have negatively 

 geotropic lateral roots protruding 

 from the ground like asparagus; 

 these are as long as one's finger, 

 or, in Sonncratia, one's arm. The 

 species of Rhizophora do not 

 possess special pneumatophores.yet 

 the upper parts of their stilt-roots 

 that are above the mud perform 

 the same function. 



That pncumatophores supply 

 subterranean parts of the trees upon 

 which they occur with oxygen was 

 proved b\' G. Karstcn and Greshoff. 

 as has been already explained^. All 

 these structures are accordingl}- 

 provided with devices for absorbing 

 ox)-gen (lenticels, sto- 

 mata, thin cork) and 

 fir transporting it (in- 

 tercellular passages in 

 the primary cortex or 

 bast). 



By means of a sketch 

 written on the spot, I 

 have attempted in the 

 following paragraphs 

 to give a description 

 •f the physiognomy 

 iif the mangrove in 

 Java • — 



• The lagoon-like bay 

 ill South Java known 

 as the '' Kindersee" is 

 separated on the south 

 from the Indian Ocean 



Fig. 224. Aviceiinia officinalis. Pnenmatophoies. 

 Mangrove, Java. Half natural size. 



Fig '2:;, Bruguiera gvmnorrhiza wiih knoc-rool^. Mangrove, low 

 tide, South Liu-ki'u. From a photograph by O. W arburg. 



^ See p. 73. 

 D d 2 



