88 



THE FACTORS [Part I 



take them up, and frequently in quantities that are not inconsiderable, even 

 if, as is proved experimentally, the plants can thrive quite normally without 



them. 



Chlorides do not appear to enter into organic compounds, but remain 

 unchano-ed in the sap of the parenchyma and in the epidermis, where they 

 can be easily micro-chemically recognized ^. 



Small quantities of sodium chloride (and of potassium chloride) are 

 apparently endured without injury by all plants. If, however, the ground 

 be watered with a 2-3% solution of common salt, most species perish in 

 a short time. The only plants to persist are halophytes, which are plants 

 living naturally in saline habitats like the sea-shore, also a few non-halo 

 phytes with marked protection against transpiration. Such plants thrive 

 excellently on a soil soaked with sea- water (2-7-3-2% sodium chloride 

 and store up considerable quantities of salt, chiefly in their stems and 

 leaves. If the concentration of the solution be further increased, however 

 even these species successively die. 



According to Wolffs 'Ash-Tables,' the percentages of chlorine in the ash of some 

 sea-shore halophytes were as follows: Armeria maritima, i2-69-i5-io; Artemisi: 

 maritima, 26-6S, though only 1-99 in its root ; Aster Tripolium, leaves 43-°°j sten 

 49-90, flowers 19-10; Chenopodium maritimum, 44-06, stem 47-oS ; Arenaria media 

 36-55 ; Plantago media, 43-53. In my own investigations the micro-chemical test foi 

 sodium chloride gave intense reactions in a large majority, though not in all, of thf 

 littoral plants of Java". 



The amount of chlorine in the ash of inland plants usuallj' does not exceed 5 % 

 but there are exceptions. 



Sodium chloride acts on the vegetable organism in part physically, since 

 like other saline solutions it impedes the osmotic absorption of wate- 

 through the roots, and in part chemically, as after its entrance into th( 

 cells it affects metabolism. 



Systematically conducted cultures investigating the influence of sodiun 

 chloride on the structure of plants were first carried out by P. Lesage, witl 

 the result that in most cases this salt caused a diminution in the leaf 

 surface, an increase in the thickness of the leaf, a lengthening of thi 

 palisade-cells, and a reduction in the intercellular spaces. Also increaset 

 hairiness was observed in some cases by Lesage. 



Experiments with cultures and a thorough investigation of the Mala} 

 littoral flora led me to the conclusion, t/iat titc viorplwlogical characteristic 

 which halophytes exhibit agree %vith those of pronounced xerophytes, evei 

 when the former grow in a wet soil, for example in littoral swamps ^. 



There is hardly one of the numerous characteristics capable of bein;| 

 regarded as protective means against transpiration in the xerophytes o| 

 a dry climate and a dry soil, that is wanting in halophytes, and this quit 

 ' Schi'.r.per, I. - Schimper, II. = See also p. 5 and ft". 



