640 BOWMAN— ECOLOGY AND 



Curve No. 2, showing the moist soil transpiration, is very short 

 and unfortunately only about two hundred records were made on 

 this series of cultures. The same characteristics are shown for 

 both curves and the lines are parallel. The two sets considered to- 

 gether show clearly that the rate of transpiration depends upon the 

 amount of moisture in the soil available for absorption by the roots. 



Curve No. i shows three things — first that mangrove seedlings 

 planted in dilutions over 35 per cent, salt transpire more rapidly 

 when planted in New Jersey soil than in shell sand. Second, that 

 similar seedlings under the same conditions in dilutions of 35 

 per cent, salt water transpire at the same rate when planted in either 

 soil and third, similar seedlings planted in water less than 35 per 

 cent, salt water transpire more rapidly when growing in shell sand. 

 These three facts can only be explained by the chemical action of 

 constituents of the soils reacting with those of the water. The 

 balance of solution for these constituents is evidently reached at 

 a concentration of about 35 per cent, salt water in the cultures indi- 

 cated by curve No. i, while the same condition of chemical equi- 

 librium is apparently reached at a concentration of 88.5 per cent, 

 salt water in the cultures of plants in merely moistened soil. While 

 it is not known what the chemical constituents of the soils are, the 

 water has been very carefully analyzed by the chemist of the U. 

 S. Geological Survey for the Laboratory Director, Dr. A. G. 

 Mayer."^ 



The explanation of the interaction of the chemical constituents 

 of these two soils with the elements of the salt water in the varying 

 concentrations used in these experiments is really a complex prob- 

 lem to be taken up by the chemist and physicist. However, it may 

 be suggested with propriety here in a paper dealing with more purely 

 botanical phases that the above interaction of the various elements 

 in the soils and salt water during ionization in the solutions proceeds 

 along the general action shown in the addition of chemicals to sea- 

 water, discussed in a recent paper by Haas.^^^ In this work by 



11^ Mayer, A. G., Annual Report of the Director of the Dept. of Marine 

 Biology, Carnegie Inst, of Washington, Year Book for 1910, p. 122. 



"8 Haas, A. R., "The Efifects of the Addition of AlkaH to Sea-Water 

 upon the Hydrogen Ion Concentration," Jour, of Biol. Client., Vol. XXVI., No. 

 2, Sept., 1916, p. 515. 



