OSMOTIC PRESSURE IN RELATION TO PLANT DISTRIBUTION 177 



separated. In the roots the pressures found are very con- 

 siderably smaller than in the leaves, and may only be half 

 as great. 



The following table contains some of Von Faber's 

 results, which were obtained by the plasmolytic method: 



TABLE XLIV. 



OSMOTIC PRESSURE OF THE EPIDERMAL CELLS OF THE LEAVES 

 OF TROPICAL STRAND FLORA. 



Rhizophora mucronata 

 conjugate, 



Avicennia alba 



ojficinalis 

 Sonneratia alba 

 Bruguiera gymnorhiza 

 Ceriops CandoUeana 

 Mgiceraa majus . . 

 Acanthus ilicifolius 

 Lumnitzera racemosa 



Atmospheres. 

 72 

 58 

 08 

 52 

 64 

 34 

 32 

 29 

 24 



The salt taste of the leaves points to the presence of 

 electrolytes as being responsible for a very considerable 

 portion of the high pressures. 



These plants have a very great power of adapting them- 

 selves to the medium surrounding their roots, and are 

 found both on coral islands and in the almost fresh water 

 of estuaries. Furthermore, it was found possible to plant 

 Rhizophora mucronata, taken directly from the sea, in fresh 

 water without causing any serious damage. 



ALG.JE. 



A fundamental distinction between marine and fresh- 

 water algae is that they are adapted to growth in solutions 

 of different osmotic pressure. That it is not owing to a 

 poisonous effect of salt water that fresh -water algae cannot 

 live in the sea is sufficiently shown by Osfcerhout's researches 



12 



