DEVELOPMENT OF PLANTS 



201 



The spores escape from the mother cell as naked bodies and 

 finally secrete cell walls and develop into new plants. 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. The female gametangium resembles 

 a flask with a long neck and is usually developed at the end of 

 a branch (Fig. 127, A), see Coleochaete. The single female 



Fig. 128. Features in the reproduction of Polysiphonia: A, branch of 

 the plant bearing clusters of male gametangia, an. B, one of the clusters 

 enlarged, showing the numerous small gametangia. C, branch on which 

 the spores derived from the gametospores are enveloped by a sac. From one 

 of these bodies, called cystocarps, the spores are escaping. 



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. 127, an; 

 128, A, B). After the discharge of the male gamete, they are 

 carried by the currents of the water to the long tube of the 



