142 THE PLANTS 



littoral and sublittoral zone, though it is reported that 

 Macrocystis pyrifera (Fig. 57), with a frond attaining a 

 length of 200 metres, goes down to a great depth on 

 the coast of Fuegia. They all love exposed places, 

 and Darwin wrote in his " Narrative of the Beagle " : 

 " I know few things more surprising than to see the 

 Kelp, or Macrocystis pyrifera, growing and flourishing 

 amongst those great breakers of the western ocean, 

 which no mass of rock, let it be ever so hard, can long 

 resist." 



Laminariaceae avoid the tropics, but occur on almost 

 all coasts in the temperate and Arctic seas. The latter 

 are rich in representatives of Laminaria, Alaria, 

 Agarum ; only three Laminariae are known from the 

 south-west coast of Africa. 



Saccorhiza bulbosa (Fig. 62), common on the coast of 

 England and Norway, is the largest European alga, 

 with a height of 2 to 4-60 metres, and a blade of 2 to 

 4 metres in length. 



Lessonia (Fig. 60) and Ecklonia (Fig. 58) are princi- 

 pally inhabitants of the southern hemisphere, only 

 three Eckloniae being known from Japan. Lessonia 

 f uscescens assumes, on the south-west coast of America, 

 the habitus of a tree with a height of 3 to 4 metres, and 

 a trunk as large as a man's thigh. From California are 

 known Dictyoneuron, Postelsia, Egregia (Fig. 59), 

 Eisenia, and the gigantic Nereocystis (Fig. 61). 



It is interesting to know that, however different the 

 adult stages of these various genera may^be, they are 

 all alike in their youngest stages. This points to a 

 common origin, and collectors gathering Kelps should 

 also look for young specimens, as there still remains 

 much to be explained with regard to the development 

 of these plants. 



The Dictyotaceae have light or dark brown ribbon- 



