33-2 



BOTANY. 



which are at first filled with granular protoplasm ; after- 

 ward each cell develops a single spirally coiled spermato- 

 zoid. When the antheridiwm is mature — i.e., when the 

 spermatozoids are fully formed — the shields separate from 

 each other, and thus expose the filaments (Fig. 329). The 

 spermatozoids escape by the rupture of the walls of the fila- 

 ment cells ; each consists of a slender spiral thread of proto- 

 plasm, thicker at one end than the other, and provided at 



the more attenuated ex- 

 tremity with two very del- 

 icate and greatly elongated 

 cilia (Fig. 229, d). By 

 means of these cilia the 

 spermatozoids movr- 

 through the water with a 

 spiral rotary motion. 



432.— Fertilization takes 

 place by the entrance of 

 spermatozoids throagh the 

 orifice between the diverg- 

 ing cells of the crown ; they 

 come in contact with the 

 apex of the carpogonium, 

 " where the cell- wall is ap- 

 parently absent ;" as a re- 

 sult of this union, the 

 cells become 

 and 



Kg. 228.— Eeproductive organs of Chara 

 fragilis. A, a central portion of a leaf, 6, 

 with an antheridium. a, and a carpogonium, 

 s, surrounded b.v tht- spirally twisted envelop- 

 ing cells ; c, crown of five cells at apex; ^, 

 sterile lateral leaflets ; /J', large lateral leaf- 

 let near the fruit ; /J", bracteoles spring ng 

 from the basal node of the reproductive or- enveloping 

 gans. -S, a young antheridium, a, and a,,., ° 

 young carpogonium. sk: w. nodal cell of thicker Walled, hard, 

 leaf ;«, iniermediaie cell hetwren 2f and the -, , i j j! 

 basal node cell cf the antheridium ; i. cavity (1 ark - COlOrea, tormillg a 

 of the internode of the leaf ; 6r, cortical cells -, „ „„i „„„;„j-; „ j.- 



of the leaf. A X about 38 ; B X 240.-After dense and resisting coating 

 ^''*^- to the fully formed carpo- 



spore within. The seed-like sporocarp thus formed soon 

 separates itself from the parent plant and falls to the bot- 

 tom of the water, where it remains until the advent of favor- 

 able conditions for germination. 



433.— In germination the sporocarp gives rise first to a 

 simple structure consisting of a single row of cells (the pro- 

 embryo), and from this the more complex sexual plant is 

 developed by the growth of a lateral bud-cell. The sexual 



