DEVELOPMENT OF PLANTS 



191 



tures already noted in the epidermis, cortex and central region 

 of terrestrial plants. The life history of the brown algae indi- 

 cates that they have undergone the same evolution as the Chloro- 

 phyceae. 



Fig. 119. Reproduction of Ectocarpus: A, branch bearing several spo- 

 rangia, sp; g, zoospore enlarged. B, branch bearing gametangia, gm. C, the 

 upper motionless gamete (female) surrounded by several still motile gametes 

 (males). D, fusion of the gametes, below the resulting gametospore. 



(a) The Simpler Brown Algae. — This development is very 

 clearly brought out in Ectocarpus, a filamentous branching form 



