XIV ILLUSTRATIONS IN THE TEXT. 



PIGS. PAGE 



14. — Enlarged node of underground stem of Char a 



delicatula (after Kuczewski) . . . .41 



15. — Symmetrical star-like stem-bulbils of Nitellopsis 

 obtusa (after Giesenhagen, H. Groves and 

 Migula) 42 



16. — Position of the reproductive organs in the four 



genera (after Sachs, Braun and Migula) . . 44 



17. — Position of the reproductive organs in Chara 



fragilis (after Strasburger) . . . .45 



18. — Development of the antheridium of Nitella flexilis 



(after Sachs) . . . .47 



19. — Mature antheridium (after Prosper) . . .48 



20.- — Development of the antherozoids (after Guignard) 49 



21. — Development of the oogonium of Chara vulgaris 



(after De Bary and Migula) . . . .51 



22. — Development of oogonium of Nitella flexilis (after 



Sachs) .52 



23. — Process of fertilization (after De Bary) . . .54 



24. — Fully developed oogonium (after Migula and 



De Bary) 55 



25. — Terminal disposition of ridges of oospore . . 58 



