igio.] 



OX THE DISTRIBUTION OF PLANTS. 



465 



Table Giving Hvdrometric Observations on Salt ;Marsh Plants of New 

 Jersey with Corrections at 15° by Mr. John C. Bechtel. 



After having discussed the theoretic methods, we must next con- 

 sider the actual study of the vegetation in the field by the use of 

 the hydrometer. 



Aids to Field Sttidy. — The equipment which was carried into the 

 field for the study of the edaphic conditions under which salt marsh 

 vegetation grows was accommodated in a light basket and consisted 

 of a meter measure, reading to decimeters, centimeters and milli- 

 meters ; a narrow, but deep, glass cylinder to hold the water upon 

 which the specific gravity determinations were made ; a tin dipper 

 to collect the water and a field note book. A narrow trenching 

 spade was carried in the hand and by this spade it was possible to 



