Chapter VIII —121— Natural Factors 



fruits to protect its seeds for a long time from injury by sea water 

 would suggest that sea currents probably played an important role in 

 the dispersal of this palm. This is supported by the fact, for instance, 

 that great numbers of these palms were already growing on the Cocos- 

 Keeling Islands, in the Indian Ocean, at the time of man's first settle- 

 ment there, in 1827. It is strange, on the other hand, that the coco 

 palm, which grows on the Pacific coast of Central America, is not 

 found on the nearby Galapagos Islands, which lie in the very path of 

 the sea currents passing from the shores of America and bearing vari- 

 ous seeds to the shores of these islands. Likewise there are few or no 

 coco palms on the Molucca Islands. These facts have led most in- 

 vestigators to believe that, although coconuts are doubtless trans- 

 ported by sea currents, this is not sufficient to insure that their seeds 

 take root in their new abode. Coconuts simply lying on the surface of 

 the soil seldom germinate; in order to germinate, they need to be 

 imbedded in the soil. Consequently, the distribution of this palm on 

 certain islands of the Pacific Ocean must have been due to their having 

 been originally planted there by man (Hemsley, I.e., p. 306). This 

 latter point of view is upheld also by Cook (igoi), who cites a number 

 of striking facts showing that the coco palm could not possibly owe its 

 distribution to dispersal by sea currents. Beccari (1916), on the other 

 hand, believes that sea-dispersal of the coco palm is not beyond the 

 range of possibility. 



Another interesting example of the fact that the mere transfer of 

 seeds to new places is inadequate to establish with certainty that the 

 seeds germinated and that the area of the given plant was thus en- 

 larged is Lodoicea sechellarum, which grows exclusively on the shores of 

 the Seychelles Islands. Prior to 1743, when these islands were dis- 

 covered, only the enormous nuts of this palm were known, found 

 floating in the sea or on the shores of India and of the Malay Archi- 

 pelago, particularly the Maldives (Hooker, 1827). Despite the fact 

 that the fruits of this palm have been carried such great distances by 

 sea currents, it grows nowhere except on the Seychelles Islands. 



Among various other investigations of this question we wish to 

 mention those of Schimper (1908) on the adaptations of fruits for 

 floating and the resistance to the action of sea water possessed by 

 seeds of plants inhabiting the shores of the islands of the Malay Archi- 

 pelago. On the basis of his observations he listed about 100 species of 

 sea-dispersed plants. From his study of mangroves growing on the 

 shores of tropical Africa he found that the species composition on the 

 eastern and western shores was entirely different. All species of the 

 western shore are found also in the West Indies, while the mangroves 

 of the eastern shore comprise elements from the East Indies. This 

 circumstance he ascribes to the strong sea currents passing these 

 shores. 



Hock (1901), having studied the distribution of littoral plants along 

 the shores of northern Germany, divides them into three groups and 

 arrives at the conclusion that the plants in the first of these groups, 

 including exclusively littoral plants, were dispersed along these shores 

 when the distribution of land and sea was the same as at present. As 

 regards the other two groups, steppe plants and arctic-alpine plants, in 



