210 J. ARTHUR HARRIS AND JOHN V. LAWRENCE. 



Rhizophora mangle shows concentrations of about 25 atmospheres 

 on the mainland shore of Biscayne Bay and 30 atmospheres in 

 the swamp at Port Henderson, Jamaica, as compared with slightly 

 over 22 atmospheres under the practically fresh-water influence 

 of the Everglades. Laguncularia racemosa shows a concentra- 

 tion of about 20 atmospheres under nearly fresh-water influence 

 at Port Henderson, from 20 to 25 atmospheres on the shore of 

 Biscayne Bay, about 25 atmospheres in the mangrove swamp 

 and about 34 atmospheres on the edges of the sterile mud flats 

 near Port Henderson. 



Apparently Amcennia is capable of developing a much higher 

 sap concentration than either of the other species investigated. 

 Thus on the shore of Biscayne Bay it showed a concentration of 

 about 33 atmospheres, whereas the maximum values for Rhi- 

 zophora and Laguncularia were about 27 atmospheres. In the 

 swamp at Port Henderson the leaves of trees of Amcennia gave 

 a freezing point lowering indicating a concentration of about 44 

 atmospheres as compared with 30 atmospheres for Rhizophora 

 and about 25 atmospheres for Laguncularia. Even the leaves 

 of seedling plants of Avicennia exhibited a concentration of 

 about 50 atmospheres as compared with the values just cited for 

 adult leaves of Rhizophora and Laguncularia. 



LITERATURE CITED. 

 Dixon, H. H., and W. R. G. Atkins. 



'13 Osmotic Pressures in Plants. I. Methods of Extracting Sap from Plant 

 Organs. Sci. Proc. Roy. Dublin Soc., N. S., Vol. 13, pp. 422-433, also in 

 Notes from Bot. Sch. Trin. Coll. Dublin, Vol. 2, pp. 154-172. 

 Garry, W. E. 



'13 Some Cryoscopic and Osmotic data. BIOL. BULL., Vol. 22, pp. 77-86. 

 Gorke, H. 



'06 Uber Chemische Vorgange beim Erfrieren der Pflanzen. Landwirthsch. 



Versuch. Stat., Vol. 55, pp. 149-160. 

 Gortner, R. A., and J. Arthur Harris. 



'14 Notes on the Technique of the Determination of the Depression of the 

 Freezing Point. Plant World, Vol. 17, pp. 49-53. 



Gortner, R. A., J. V. Lawrence and J. Arthur Harris. 



'16 The Extraction of Sap from Plant Tissue by Pressure. Biochem. Bull., 

 Vol. 5, pp. 139-142. pi. i. 



Harris, J. Arthur. 



'16 An Extension to 5.99 of Tables to Determine the Osmotic Pressure of 

 Expressed Vegetable Saps from the Depression of the Freezing Point. 

 Amer. Jour. Bot., Vol. 2, pp. 418-419. 



