1910.] OX THE DISTRIBUTION OF PLANTS. 489 



algx, both green and brown, which are found in various stages of 

 their existence at different times in these ponds/ ^ 



Sections of Salt ^NIarsh Soil. 

 A detailed study of the various sah marsh soils along the Xew 

 Jersey coast was begun coincidently with a study of the salt content 

 of the soil by means of the hydrometer, but these observations have 

 not been carried to completion. A few notes on some of the condi- 

 tions observed may not be out of place. Taking a sample of the 

 muck soil in the middle of an area of the ^lanasquan salt marsh 

 covered with Spartiiia patens, we find its total depth to be about 104 

 cm. From this a block of peat was cut 57 cm. thick. The first 21 

 cm. at the top was of one color, consisting of 12 cm. of a fibrous 

 root material and 9 cm. of a less strongly fibrous layer. The first 

 12 cm. represent the remains of the cover plant, for this part gave 

 rise to new plants of Spartiiia patens when the soil was laid flat 

 along the side of the cut. Below these upper fibrous layers followed 

 a lighter brown fibrous layer, 14 cm. thick, and then 7 cm. of a black 

 fiberless layer followed by 16 cm. of a brown fibrous layer where 

 the hollow pipe-stem-like remains of the rootstocks of Sparfina 

 striata maritiina occur. This section of peat clearly indicates a suc- 

 cession of vegetation types. The marsh deposits began in submerg- 

 ing salt water, because the remains of Spartiiia sfricta inaritiina are 

 found in the lower layers. Then sand and clay material was depos- 

 ited on which Spartiiia patens began to build up successive layers of 

 peat. This was formerly explained by a change of coast line, but 

 the suggestions of Johnson (see ante) that it may indicate a change 

 of tidal'level seems to be worthy of consideration in a study of the 

 deposits of peat in the salt marshes of Xew Jersey, where the coast 

 line is under constant change so as to profoundly influence the 

 height of the tides in the rivers and embayments along the shore. 



Economic Coxsideratioxs. 

 The salinity of the water, which can be determined by the hy- 

 drometer, is the determining factor in the distribution of salt marsh 



" MacDougal, D. T., " Annual Report of the Director," Dept. Bot. Re- 

 search Carnegie Institution of Washington, 1910, 56. 



I'ROC. AMER. PHIL. SOC, L. 20I GG, PRINTED AUC. 26, I9II. 



