506 J. ARTHUR HARRIS 



CONCLUSIONS 



The osmotic concentration of the tissue fluids of epiphytic Brome- 

 liaceae, Orchidaceae, Piperaceae, and Gesneraceae is far lower than 

 that of terrestrial vegetation. 



In the Jamaican montane rain forest where direct comparisons for 

 individual habitats are possible, the epiphytes show from 37 to 60 per 

 cent of the concentration characteristic of herbaceous terrestrial 

 vegetation, and from 28 to 45 percent of the concentration of ligneous 

 terrestrial vegetation. 



In the Bromeliaceae, Orchidaceae, and Peperomia of the Piper 

 aceae, the osmotic concentration of the species of the Jamaican mon 

 tane rain forest is lower than that of the species of the hammocks of 

 subtropical Florida. 



At some future time I hope to deal with the problem of the osmotic 

 concentration of cryptogamic epiphytes and to obtain data on the 

 inorganic and organic constituents of the fluids of epiphytes which 

 will justify further discussion of the physiology of these ecologically 

 remarkable forms. 



LITERATURE CITED 



Harris, J. A. 1917. Physical chemistry in the service of phytogeography. Science, 



n. ser. 46: 25-30. 

 . 1918. On the osmotic concentration of the tissue fluids of desert Loran- 



thaceae. Mem. Torrey Club 17: 307-315. 

 Harris, J. A., and Gortner, R. A. 1914. Note on the calculation of the osmotic 



pressure of expressed vegetable saps from the depression of the freezing point, 



with a table for the values of P for A = .001 to A = 2.999. Amer. Journ. 



Bot. i: 75-78. 

 Harris, J. A., and Lawrence, J. V. 1916. On the osmotic pressure of the tissue 



fluids of Jamaican Loranthaceae parasitic on various hosts. Amer. Journ. 



Bot. 3: 438-455. Diag. 1-2. 

 . 19170. The osmotic concentration of the tissue fluids of Jamaican montane 



rain forest vegetation. Amer. Journ. Bot. 4: 268-298. 

 . 19176. Cryoscopic determinations on tissue fluids of plants of Jamaican 



coastal deserts. Bot. Gaz. 64: 285-305. 

 . With the co-operation of R. A. Gortner. 1916. The cryoscopic constants 



of expressed vegetable saps as related to local conditions in the Arizona 



deserts. Physiol. Res. 2: 1-49. 





