DEVELOPMENT OF PLANTS 



211 



can be pointed out. Singularly both the spores and gametes 

 have lost their motility. The sexual method of reproduction is 

 the most complicated among all the algae, and even in the 

 simplest form is far in advance of any method heretofore noted. 



FIG. 125. Common forms of the Red Algae: ^4, a leaf-like form, Deles- 

 seria. B, a branching thread-like form, Ceramium. C, a branching form 

 covered with delicate hairs, Dasya. 



The female gametangium resembles a flask with a long neck and 

 is usually developed at the end of a branch (Fig. 126, A}, see 

 Coleochaete. The single female gamete is found at the base of 

 the flask. The male gametes are produced singly in small cells 

 also at the ends of branches and they are often closely aggregated 

 in dense clusters (Figs. 126, an; 127, A, B). After the discharge 

 of the male gamete, they are carried by the currents of the 

 water to the long tube of the female organ. The wall of the tube 

 at the point of contact is now absorbed and the male gamete 

 passes down the tube and fuses with the female. The gameto- 

 spore does not germinate and produce a new plant similar to the 

 one that bore the gametes. On the other hand, it produces a 

 number of branches (Fig. 126, B, C), the terminal cells of which 

 develop as spores (Fig. 126, D). The mode of sexual repro- 



