TEMPERATURE 131 



surf of the sea ; and, again, others thrive well only in 

 quiet pools. Algae are admirably adapted to profit by, 

 or to withstand, the strong force of the waves. Some 

 surf-loving algae have long flexible stalks that follow 

 the movement of the water, while the blades at their 

 top swing to and fro in the waves ; other algae in the 

 same locality can withstand the action of the waves, 

 because their tissues are encrusted with carbonate of 

 lime. 



Temperature. — Some algae can endure great differ- 

 ences of temperature without damage. Kjellman ob- 

 served in Nameless Bay, Nova Zembla, Enteromorpha 

 minima, a green alga, in fresh water of o° C, and in 

 sea water of 4 to 5 C. In the tropics the algae are 

 exposed to the glare of the sun during ebb tide, and 

 in the Arctic regions Kjellman found Laminariae 

 thriving well in a temperature of — 2° C, and on being 

 exposed at ebb-tide, they withstood even a tempera- 

 ture of -20° C. 



Algae want, however, as a rule, a more congenial 

 temperature, and if the coast of Norway has such a 

 decidedly different vegetation from the coast of ad- 

 jacent Polar lands, this is mainly due to the North 

 Atlantic Drift, whose influence is felt even on the west 

 coast of Nova Zembla. Still more striking, perhaps, is 

 the difference on the west and east coast of South 

 Africa. On the latter, bathed by the Mozambique cur- 

 rent coming from the tropics, tropical and subtropical 

 algae flourish ; while on the west coast, with its Benguela 

 current partly coming from the Antarctic, we find a 

 totally different vegetation. Many more examples might 

 be cited, all showing clearly the great influence which 

 the temperature of the sea has on vegetation. Pro- 

 fessor Farlow describes how Cape Cod, in North 

 America, is a boundary between two vegetations. To 



