THE COLDEK, TEMPERATE ZONE. 91 



though in the Southern Temperate Zone "it girds the 

 globe/' this is not the case either in the Tropics or in the 

 Northern Hemisphere. The southern limits of the belt 

 which it forms were often observed as " between the South- 

 ern Sea and the Southern Ice, within which there is no 

 vegetation." 



On the southern border the boundary of the " Macro- 

 cystis sea" is regulated by the position of the ice : where 

 open sea extends, as it does in the longitude of New Zea- 

 land, to the 65th degree, this plant is found as far as 64 : 

 its northern limit depends " on the currents and temperature 

 of the water." As regards the temperature of the ocean, 

 "it neither enters the Tropics of the Atlantic, nor passes 

 up the shores of Africa, or into the Indian Ocean; whilst 

 it does inhabit the whole surface of the Pacific Ocean and 

 the west coast of both Americas." 



It is interesting to trace the influence of the other agent, 

 namely the currents, by whose action the Macrocystis is 

 carried far and wide. " The South Polar current divides at 

 Cape Horn, one portion following the west coast of South 

 America to Cape Blanco and the Galapagos Islands under 

 the Equator, carrying the Macrocystis with it, which then 

 enters the cold waters which flow from the Arctic islands 



