26 



ELEMENTARY STUDIES IN BOTANY 





food) within a swollen cell, and small ciliated sperms having 

 escaped from small cells (6) ; while the illustration of Fucus 



(Fig. 20) shows a very 

 large egg surrounded by 

 numerous, small, and very 

 active sperms. 



19. Differentiation of 

 sex-organs. - - In such 

 Algae as Ulothrix (Fig. 7, 

 C), an ordinary vegeta- 

 tive cell, without any 

 change of form, produces 

 gametes. In other Algae, 

 as Ectocarpus (Fig. 16, 

 E), the cells that produce 

 gametes differ in form 

 from the vegetative cells, 

 just as the cells that 

 produce spores (A) differ 

 from them. Just as the 

 spore-producing cells that 

 become different from the 

 vegetative cells are called 

 sporangia ( 15, p. 22), so 

 these gamete-producing 

 cells that become differ- 

 ent are called gametangia 

 (" gamete -cases")- A 

 gametangium, therefore, 



Vocc J.' ig JL&J uvjuuaaj-ung u 10,11. unco jjn_m.u.<Jiii^ , j_l~ X * 



antheridia ; B, an enlarged view of a branch IS a SCX-Organ, that IS, a 



structure that produces 

 sex-cells (gametes). 

 When the gametes become plainly different, so as to be 

 called eggs and sperms, the gametangia that produce them 

 become different and receive distinguishing names. The 



FIG. 18. Fucus: A, a chamber in the body 

 (see Fig. 12) containing branches producing 



bearing antheridia, in which the sperms can 

 be seen. After THURET. 



