62 NATURAL HISTORY OF 



range, greater "than that of any of the larger Algce,'' the 

 reader will be able to judge from the following account, also 

 from the pen of Dr. Hooker : — " The Macrocystis girds the 

 globe in the southern temperate zone, but not in the tropics 

 or northern hemisphere, and this is a most curious trait in 

 its history. We may first, however, trace the southern edge 

 of the belt which it forms, and we are the better enabled to 

 do so, because the limits of its existence as a floating plant 

 were observed in six different longitudes in the passage of the 

 Antarctic Expedition as often between the Southern Sea and 

 the southern ice, within which there is no vegetation. The 

 southern boundary of the Macrocystis sea is very much deter- 

 mined by the position of the ice, and the northern by the 

 currents and temperature of the water. Thus, in the longi- 

 tude of New Zealand, where open sea extends to the 65th 

 degree, this plant is found as far as 64°, the specimens having 

 probably been drifted originally from Kerguelen's Land or 

 the Crozets, which are the great nurseries for it in the 

 eastern hemisphere, and from whence all these drifting 

 islets have been wafted which occur between their longitude 

 and Cape Horn. In the longitude of Cape Horn, 58° or 60° 

 is the highest parallel it attains, for it has not been found 

 among the South Shetlands. Farther east, in the South 

 Atlantic, its parallel is probably still lower, till in the 

 meridian of the Cape of Good Hope it is 40° removed from the 

 Pole, being no farther south than 50° 30'. There the Atlantic 

 Ocean specimens are derived from the southern extreme of 

 America and the neighbouring islands. Its northern range, 

 on the other hand, is dependent — 1st, on the temperature of 

 the ocean, for it neither enters the tropics or 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 



