110 PLANTS, SEEDS, AND CURRENTS 



retain their vitality in the dry condition for five months, an implica- 

 tion arising from his results being that the seedlings, when they fall 

 into the sea, would often continue their hypocotylar growth in length 

 for an inch or two (pp. 96-98). His observations in the Pacific on 

 the proportion of germinating fruits of Rhizophora mangle possessing 

 more than one seedling, and on the extreme length of the hypocotyl, 

 are here supplemented (pp. 98-99). 



3. He was unable to discover in the West Indies any persistent 

 evidence of the dimorphism observed by him in Rhizophora mangle 

 in Ecuador, nor did he come upon any seedless form of Rhizophora 

 corresponding to the " Selala " of Fiji (p. 99). 



4. There are next given the results of a number of observations 

 made in the West Indies, Ecuador and the Pacific islands on the 

 influence of varying degrees of salinity on the station of Rhizophora 

 mangle (pp. 99-101). 



5. Remarks are then made on the infiltration of sea- water into the 

 interior of the Great Morass of the Black River district in Jamaica, 

 and in this connection is noted the occurrence of colonies of Rhizophora 

 mangle in the midst of this great swamp (pp. 101-102). 



6. The underflow of sea- water up tropical estuaries is regarded as 

 an important factor in determining the stations of estuarine plants, 

 and the subject is illustrated by the cases of the Black River in 

 Jamaica and of the Guayas or Guayaquil River in Ecuador (p. 102). 

 In this matter Prof. Harshberger's hydrometric and thermometric 

 observations on the stations of plants in the tidal estuaries of New 

 Jersey afford instructive lessons for similar investigations in tropical 

 estuaries (pp. 103-104). 



7. Attention is directed to the numerous large fresh-water springs 

 that well up in the midst of the Black River Morass, and to the rich 

 growth of aquatic plants at their borders (p. 104). 



8. The author then deals at length with the vegetation of the 

 Black River district, especially of the Great Morass, as well as of the 

 similar region of swamp around Savanna-la-mar (p. 105). He also 

 describes the vegetation of the Great Lake at Pondside near the 

 Black River (p. 107). The physical and botanical features of the 

 Salt Lakes in the same neighbourhood are treated in detail (p. 107). 



