INTRODUCTION TO CRYPTOGAMIC BOTANY. 



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such cases, the only semblance of a root is a little dilatation of 

 the base, or occasionally a few divisions, consisting either of a 

 single row of cells, or, where necessity requires, of a larger mass. 

 In the higher Algse, as in the large species of Luminaria, the 

 rootlike processes acquire a considerable size, the exposure to 



Fig 26. 



Branch of Callithamnion Hookeri, from Eug. Bot. t. 2938, compared 

 with specimens from Mrs. Griffiths, and Mr. Ealfs. 



heavy swells and stormy seas necessitating a strong adhesion 

 to resist the mechanical powers opposed to them. Where 

 there is little danger of disunion the attachment is propor- 

 tionally slight; and where, as in Sargassutn and Macrocystis, 

 the individuals are destined to float as parts of large fields, 

 sometimes miles in extent, on the surface of the waves, the 

 plant often separates from its primary attachment altogether, 

 and multiplication takes place by a constant re-division of the 

 frond, as in the lower Alga;. 



74. The simplest Algoe consist of mere cells; more complicated 

 forms arise, first, from the articulation of such cells, end to 

 end, by means of transverse partitions, and then, by the addi- 

 tion of lateral cells by means at once of transverse and longi- 

 tudinal dissepiments. According to the proportion in which 

 these two processes are carried out, we have, on the one hand, 



