224 



PART III. THE CLASSIFICATION OF PLANTS. 



The leaves vary in form. In some cases (e.g. Caulerpa, Fig. 

 162; Sargassum) they resemble the foliage-leaves of the higher 



xu 



B. 



c. 



FIG. 160. Growing-points of Algoe. A apical growing-point, with apical cell, of 

 Sti/pocaulon, scoparium (x30). B intercalary trichothallic growing-point (where the 

 transverse lines are close together) of Desmirestia liguiatain longitudinal section (x 60). 

 C apical growing-point, with apical cell, of Chatoptc.ris plumosa (x 40) (after Falkenberg). 



plants; in others, (e.g. Cladosteplms, Chara) they resemble the 

 stem and its branches, but are distinguished by their limited 



growth : in others again (e.g. 

 Polysiphonia and other Rho- 

 dophycese, Fig. 161), they 

 are filamentous and hair-like. 

 The morphology of the 

 reproductive organs is dis- 

 cussed in connexion with the 

 processes of reproduction. 



The Reproduction of the 

 Algse is effected in various 

 ways. Vegetative multipli- 

 cation takes place in the 

 unicellular forms (e.g. Cyano- 

 phycese, Protococcoideee, Des- 

 midieee, etc.) by cell-division, 

 in some of the higher forms 

 (e.g. Sphacelaria, Chara, 

 Melobesia) by means of mul- 

 FIG. i6i.-roiy S i P honia(Herposiphonin)(arter ^Hular gemmae (see p. 68). 



Naegeli). The dorsiventral horizontal stem 

 bears the leaves (/) on the dorsal surface; the 

 root-hairs (r) on the ventral surface; and the 



branches (a b c) on the flanks. 



Non-motile Cells, with a Cell 



Irol i , i i i i i 



*"*? WhlCh ^ P robab] y 



gemmee, are thrown off by 



