77 



increasing in length upwards and the blade is growing 

 at its base. The Lessonia type, to which the genera 

 Dictyoncuron, Postelsia, Nercocystis, and Macrocystis 

 conform, is characterised by greater complexity of 

 fronds, which are branched in all cases except 

 Dictyoneuron, and this branching originates in a 

 splitting at the growing-point, causing unequal 

 divisions in Macrocystis and equal ones in the other 



FIG. 13. Laminarla digitata. 

 Reduced. 



FIG. 14. Agannn Turner i. 

 Reduced. 



genera. In Lessonia, which has numerous blades 

 borne at the ends of the dichotomously branching 

 stalk, and as many growing-points as there are 

 blades, the branching arises in consequence of a 

 longitudinal slit in the middle of the growing-point. 

 This slit in the growing-point at the base of the 

 blade extends, or appears to extend, both upwards 

 and downwards as the blade and the stalk increase 



