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little rootlet-like outgrowths to the sub- 

 stratum. Some varieties retain this 

 shape throughout their lives, reaching 

 perhaps an enormous size. Thus Lami- 

 naria saccharina increases in size until 

 the leaf is a foot wide and more than 

 six feet in length. In others the prim- 

 itive lamina becomes split in the grow- 

 ing region, which lies between the 

 summit of the stipe and the base of 

 the lamina, and the mature plant is 

 quite different in appearance from the 

 young form. By repeated splitting of 

 the lamina, the hollow, massive stipe of 

 Postelsia, a foot or so in height, comes 

 to bear a tuft of a hundred or more 

 slender, lanceolate, furrowed leaflets, giv- 

 ing to the plant somewhat the aspect 

 of a miniature palm, hence its common 

 designation as the "sea palm." Simi- 

 lar repeated splittings in the closely 

 related Nereocystis result in the produc- 



