PHYSIOLOGY OF THE RED MANGROVE. 651 



Scientific Proceedings of the Royal Dublin Society and reviewed for 

 Plant World by E. W. Berry. This work deals exhaustively with 

 the buoyancy of seeds and his observations on seeds of over 900 

 British plants show that the more buoyant forms are inhabitants 

 of streams, banks or seashores. The results showed that 85 per 

 cent, sunk at once or within a week, 5 per cent, floated i to 4 weeks, 

 33 per cent, i to 6 weeks, 1.9 per cent. 6 to 12 months and 4.4 per 

 cent, floated over 12 months. In consideration of these results and 

 as the life and dissemination particularly of the viviparous seed- 

 hngs is dependent on buoyancy it seemed worth while to undertake 

 some investigation of this and related phenomena concerned with 

 dissemination. Guppy has done such excellent work and made such 

 complete observation on the buoyancy of the mangrove seedlings 

 that no work on buoyancy was required, that writer's latest book^*^ 

 giving a summary of observations along this line. Harshberger's 

 works^'**"^*^ on the ecology of South Florida also were of a simu- 

 lating effect and a helpful reference in the present work on the 

 mangrove of the region, as well as Webber's notes^*'' and the jour- 

 nals of the Agassizes.^*^"^*^ 



The relations of these mangroves to their environment have 

 been a subject of much interest to ecologists and botanists in gen- 

 eral from Theophrastus to the present, and many philosophical dis- 

 cussions have been given concerning their origin and adaptation to 

 their habitats. In these adaptations, however, they only perhaps 

 show in more marked degree what all plants of strand floras show, 

 viz., strongly developed xerophytic characters, in spite of the fact 

 that the environment is aquatic. These characters have been fully 

 discussed by such writers as Holtermann^'*^ on the effect of climate 



^*^ Guppy, H. B., loc. cit.. p. log. 



!*■* Harshberger, J. W., " Vegetation of South Florida," Trans. Wagner 

 Inst, of Sci., Vn., 3, 1914. pp. 74-80. 



145 Harshberger, J. W., " Phytogeography of North America." 



1*6 Webber, J. H., " Strandfiora of Florida," Science (N, S.), VHI,, 1898, 

 p. 658. 



i-*' Agassiz, Louis, " Florida Reefs." 



148 Agassiz, Alexander, " Three Cruises of the Blake." 



149 Holterman, Carl, " Der Einfluss des Klimas auf den Bau der Pflan- 

 zengewebe," Leipzig, 1907. 



