1909.] NATURAL SCIENCES OF PHILADELPHIA. 397 



another of Scirpus pungens ( + ), while Panicum crus-galli (I) and 

 Leersia oryzoides (±) fill the interspaces between some of the afore- 

 mentioned groups of species. Hibiscus moscheutos occurs sparingly 

 along the edge of the swamp. Bidens chrysanihemoides appears 

 abundantly in the Fall of the year. 



Relation of Salt Marsh to Salt Water. 



Sodium chloride in solution is known to have strong plasmolytic 

 properties, removing water from living cells, when these aie subjected 

 to its action, and hence causing the protoplasm to contract away 

 from the cell walls. Ordinary plants are soon killed when exposed 

 to the action of salt or salt water, and yet we have a group of plants, 

 the so-called halophytes, which possess great powers of resisting the 

 action of sodium chloride in solutions as strong as sea water. The 

 sea beach plants are excluded from consideration, because Kearney 10 

 has shown that the salt content of the shore sand is a negligible quan- 

 tity, and that some cultivated soils contain a larger percentage of 

 •common salt than the beach sand, so that of the strand plants the salt 

 marsh species are the only ones which belong to the halophytic class 

 of plants. Schimper" has called attention to the fact that any con- 

 siderable amount of salt in the cell sap is detrimental to the plant, and 

 that this fact explains the probable cause of the characteristic halo- 

 phytic modifications, which have to do with reducing the transpiration 

 current, which accounts for the abundant absorption of water with 

 various salts of the soil in solution. Warming, however, replied that 

 the reduction of transpiration would cause the increase of the salts 

 in the cell sap, and he suggested a theory, which is now the current 

 one, viz., that the protective contrivances, such as hairs, sunken 

 stomata, succulency, etc., against strong transpiration are necessary 

 in halophytic plants, because absorption of water from a salt solution 

 is slow and difficult. 



In the absence of experimental data which will enable us to arrange 

 the salt niarsh plants of New Jersey into a series with reference to their 

 greater or less power of resistance to salt water, 12 the following general 



10 Kearney, T. H. : Are Plants of Sea Beaches and Dunes True Halophytes? 

 The Botanical Gazette, XXXVII: 424-436, June, 1904. 



11 Schimper, A. F. W.: Ueber Schutzmittel des Laubes gegen Transpiration, 

 besonders in der Flora Java's. Sitzb. Acad. Berlin, 1890: 1045; Die indo-malayische 

 Strandflora. Botan. Mittheil. aus den Tropen, l 3 : 1-204. 



13 This was written in 1908. During the summer of 1909 the writer by means 

 of a hydrometer (see previous note) made a detailed study of the various salt 

 niarsh plant habitats. 



