GREEN ALGAE 



39; 



pairs (Fig. 335, i.). In Bryopsis the size is unequal (ii.) ; wliilc Codiin, 

 shows still greater inequality (iii.). This is again more marked >n 



r^:n^ 



I'IG. 335. 



Gametes of various Siphonales, and Siphonorladiales, illustratiiiK difTerentiatinn 

 of male and female. i=^f^/afci(/an'a, isoganictcs ; ii = i;rr<>/!>4«.s ; iii:^(Wiiim: 

 iv = Spkaetoplea ; v = Vaucheria. In iv. and v. the large egg is stationary, while 

 the smaller spermatozoid is motile. (Taken from Oltmanns' Algaf.) 



Sphaeroplea, where the large egg is non-motile (iv.), a condition still 

 more accentuated in Vaucheria (v.), which is the most advanced of 

 all in sexual differentiation. 



The sex-organs of Vaucheria arise 

 close together as short lateral branches 

 (F. sessilis), or borne together on the 

 same branch (F. terresiris, Fig. 336). 

 The antheridia are horn -like, curved 

 bodies, the oogonia are oval. In the 

 antheridium a septum cuts off the 

 multi-nucleate protoplast from the 

 parent tube : each nucleus becomes the 

 centre of a spindle-shaped sperma- 

 tozoid ; and these escape, with their 

 paired cilia pointing fore and aft, 

 through an opening at the distal end. 

 The oogonium also at first contains 

 numerous nuclei embedded in proto- 

 plasm stored with many globules of oil. ■ ^ iii -o 

 But, as theovum matures, all the nuclei soxuai branch o» imwktns i^rmtttt. 



, ,,11 t- txariiiK jliMallv « runr«l an'H'-- <•••"< ^"i 



but one wander back into the parent right and left oval oofonJa. 



