CURRENT- CONNECTIONS IN S. HEMISPHERE 311 



the agency of the South Equatorial Current. To its tropical Atlantic 

 coasts the Main Equatorial Current would bring drift from tropical 

 West Africa ; whilst in the stream of the South Atlantic Connecting 

 Current would be carried materials from its extra-tropical shores to 

 South Africa (pp. 299-300). 



6. With regard to Africa it is shown that its opposite coasts 

 display the same reciprocity in the exchange of drift that is exhibited 

 by South America. Whilst the tropical borders on the west would 

 distribute drift to the New World through the agencies of the equa- 

 torial currents, those on the east would be the recipients of drift 

 from tropical North-west Australia and from Malaya. So also the 

 western extra-tropical coasts would receive drift from high latitudes 

 in South America, and the corresponding eastern coasts would supply 

 it to the southern borders of Australia. The connections across the 

 Indian Ocean with Malaya and Australia are then discussed. In 

 the first case it is shown that Malaya is the giver and Africa the 

 recipient, the drift being transported in the South-east Trade Current 

 to equatorial East Africa. The general effect of the alternating 

 influence of the monsoons would be to restrict the arrival of Malayan 

 drift to the period of the north-east monsoon. In the other half of 

 the year it might be stranded almost anywhere on the shores of the 

 northern half of the Indian Ocean. As regards Australia, it is shown 

 that whilst drift from its north-west shores would reach tropical 

 East Africa, drift from its extra-tropical western coasts might reach 

 Cape Colony. But as concerns Australia, Africa may be the giver 

 as well as the receiver, since South African drift may arrive on the 

 south coasts of Australia by the way of the Agulhas and West Wind 

 Drift Currents (pp. 300-305). 



7. In applying these principles to the distribution of littoral and 

 estuarine plants in the southern hemisphere it is observed that 

 seed-drift travels west in tropical latitudes and east in temperate 

 latitudes. Whilst in the temperate zone we look to the west for 

 the source of plants that are dispersed by currents, in the tropics 

 we look to the east. In the tropics we look for South American 

 plants in North-east Australia, for Malayan and Australian plants 

 in East Africa, and for West African plants on the shores of 

 Brazil and of the Guianas. In the temperate zone we look for 

 Fuegian plants in South Africa, Southern Australia, and the 

 northern end of New Zealand; for South African plants in 

 Southern Australia; and for plants of southern New Zealand in 

 South Chile. Though there is often a marked change in latitude, 

 the rule holds good that for the source of the elements common 

 to littoral and estuarine floras on both sides of an ocean we must, 

 as far as the agency of the current is concerned, look to the east 

 in the tropics and to the west in the temperate zone (p. 306). 



8. In illustration of these principles in the temperate zone the 

 instances of Convolvulus soldanella and Sophora tetraptera are taken. 

 In the tropics, it is shown that whilst in the Indian and Atlantic 

 Oceans the littoral and estuarine floras on the opposite sides are 

 closely similar, the fusion has been retarded in the Pacific on account 

 of the great width of the ocean and the paucity of suitable stepping- 



