Fortunate Islands 



have been most carefully studied, and indeed their story 

 is a romance in itself. 



There are from 80 to 120 of these navigators 

 belonging to the most various orders, but all are well 

 able to take a long sea voyage. 



Their seeds or fruits are able to float for a very long 

 time vi^ithout being in any way injured. Caesalpinia, 

 for instance, has been allowed to float for two and a 

 half years in salt-water, and many others have survived 

 for a year and have germinated successfully afterwards. 



Caesalpinia bonducella has been carried from across 

 the Atlantic to the Orkneys, Ireland, Hebrides, and 

 Scandinavia, and also to St. Helena. Robert Brown 

 succeeded in growing a plant from one of these Ameri- 

 can-Irish seeds. 



Perhaps another of them (Entada scandens) is an even 

 more efficient navigator, for it has been found in the 

 Azores and in Nova Zembla, as well as in all the places 

 just mentioned. Seeds from the Azores germinated 

 at Kew.^ 



These two are Leguminosae and are able to float in 

 consequence of their hard, woody, and hollow pod, which 

 is in fact very like two shallow wide punts joined together 

 along their sides and enclosing the seed in an air-tight 

 compartment. 



Most of the navigators have porous or buoyant tissue 

 somewhere in the fruit or seed due to air cavities or 

 hollows. 



Now waterside plants and especially submerged 

 plants are always remarkable for the number of air 

 channels or intercellular spaces. Such cavities are 

 almost always to be found in water plants, and are due 

 to the special necessity of preserving oxygen when sub- 

 merged or growing in mud. So these navigator plants 

 again show a strange example of fitting reaction. This 



279 



