78 PLANTS, SEEDS, AND CURRENTS 



seed-drift that must be rushed in a few months across the tropical 

 Atlantic in the streams of the North and the Main Equatorial Currents. 

 It is, as we have seen, only in the tropics that currents play an 

 important part in plant distribution. For ages these two currents 

 have been bearing their burdens westward direct from the African 

 shores. Except for the occasional intervention of a counter-equatorial 

 stream, as before described, there would be no direct return route 

 from the American shores. 



Drift carried by Currents round Cape Horn, Cape Agulhas, 

 and the North Cape. — It is noteworthy that drift has been known 

 to double all the three great headlands which form the extremes of 

 the continents of South America, Africa and Europe, towards the 

 poles. Reference has already been made to this matter in different 

 connections. Thus on p. 63 it is shown that bottles can be carried 

 from off the coast of Natal round Cape Agulhas and across the 

 South Atlantic to tropical Brazil, and from the Pacific side of Tierra 

 del Fuego to the Falkland Islands. In neither case would the con- 

 nection appear to be a frequent one; but the transference of seed- 

 drift from the Indian Ocean to the South Atlantic would probably 

 be the most effective. With regard to the doubling of the North 

 Cape it is well known that West Indian seed-drift is carried by the 

 Gulf Stream to the vicinity of this headland, and in Chapter II. it 

 is pointed out that it may even double this promontory and reach 

 the shores of the White Sea. I have no example of this having been 

 accomplished by bottle-drift ; but that bottles can reach the vicinity 

 of this cape from the other side of the Atlantic is shown in the U.S. 

 Pilot Chart for December 1908, in the case of one dropped overboard 

 off Cape Hatteras. 



Summary 



1. As indicative of the track followed by the drifting seed and of 

 the time occupied in the traverse of the Atlantic the behaviour of 

 the drifting bottle affords very important data (p. 46). 



2. After dealing with the sources of the materials employed, the 

 value of bottle-drift for the study of the dispersal of seeds by currents 

 is discussed. The small proportion of recoveries is pointed out 

 (p. 48), and it is shown that the difficulties connected with the 

 delays in the recovery are not so formidable as they at first seem 

 (p. 49). The water-logged derelict from off Cape Hatteras, the 

 baulk of mahogany from West Indian islands, the living turtle from 

 the warm latitudes of the New World, the floating bottle containing 

 the record of its start in Cuban waters or in Florida seas, the buoyant 

 seed that could have grown only in the West Indies or on the tropical 

 mainland of America, all tell the same story when they are stranded 

 on our European beaches (p. 48). 



3. The treatment of the subject is divided into two parts: in the 

 first place, the tracks followed ; in the second place, the time occupied 

 by the drifting bottle; and in order to give method to the inquiry 

 the accomplishment of the circuit of the North Atlantic is first 

 dealt with. It is remarked that the circulatory movements of the 

 currents in this ocean are equally well illustrated, whether the 



