484 HARSHBERGER— SALT MARSH POOLS. 



small umbel of white flowers. During part of the day it is ex- 

 posed to submergence by salt water and during the rest of the 

 day, its leaves are subjected to the action of air and ..sunlight, while 

 its roots and creeping stems are influenced by fresh water. Such 

 a plant must change its osmotic relations several times a day, 

 alternately being exposed to the action of salt and fresh water. 

 It was under such conditions of environment that the plant was 

 first detected in New Jersey by Thomas Nuttall, who found it near 

 " Egg Harbor," apparently near Beesley's Point. 



Soon the typic salt marsh species such as Spartina glabra, 

 S. patens, Distichlis spicata, Juncus Gerardi gain access to the 

 barren ground occupied by the pioneer species (Plate XIIL, Fig. 2; 

 Plate XIV., Fig. i), which are gradually replaced by the plants 

 which are dominant in the salt marsh. After these vicissitudes of 

 salt marsh existence, we find the climax vegetation restored, and 

 the areas formerly denuded by the smothering action of drift ma- 

 terial and alg3e appear again, and the usual flat, featureless, meadow- 

 like physiognomy of the salt marsh surface appears again (Plate IX., 

 Fig. i). In the study of the origin of salt marsh pools, we have 

 traced the successional history of plants which are normal con- 

 stituents of the salt marsh flora, but which become associated to- 

 gether in a dififerent way upon the genesis of the pools of larger 

 and smaller size, which are typic features of the meadow-like ex- 

 panses of our eastern Atlantic halophytic marshes. As the genesis 

 of the pools with their algse and other species of flowering plants 

 are due directly to the action of the tides in carrying the flotsam and 

 jetsam of salt plants over the surface of the marsh, so with the 

 elevation of the marsh, and the absence of the daily or periodic 

 flooding of the surface with sea water, we find a cessation in the 

 formation of tidal pool formation and the permanence of a level, 

 uniform surface of salt marsh, which may later change its physi- 

 ognomy and floral character, when fresh-water conditions come to 

 prevail. The ecologic succession of such converted areas of salt 

 marshes is an entirely different problem, but its essential feaures 

 have been described previously in a paper^ entitled " The Reclama- 

 tion and Cultivation of Salt Marshes and Deserts." 



1 Harshberger, John W., Bulletin of the Geographical Society of Phila- 

 delphia, July, 1907. 



