88 



PLANT MORPHOLOGY 



Its nucleus degenerates. The nonmotile male cell, or spermatium, is 

 carried by water currents. After coming in contact with the trichogyne, 

 it becomes binucleate. Both of the male nuclei may enter the trichogyne 

 but only one passes into the carpogonium, where it fuses with the egg 

 nucleus. The other male nucleus does not function. 



Fig. 74. Nemalion Inhricitm, X 700. A, portion of plant with four antheridial branches 

 consisting of groups of small cells, each producing a single spermatium; B, a carpogonial 

 branch, terminating in a carpogonium with its slender trichogyne to which a spermatium 

 is attached; C, a cjstocarp, composed of fertile filaments that cut off terminal carpospores. 



Following fertilization, many short filaments, called gonimohlasts, arise 

 from the carpogonium and at the tip of each a carpospore is organized. 

 After a carpospore is shed, another may be cut off from the cell behind it. 

 It is only in the Bangiales that carpospores are produced by direct division 

 of the zygote. In Nemalion the carpogonium, fertile filaments, and 

 carpospores collectively form the cystocarp (Fig. 74C). The carpospores, 

 upon being set free as naked, nonmotile cells, develop into sexual plants. 



