PLATE II. 



FRESH-WATER 



1. Spirogyra, in conjugation 7. Vaucheria, Sexual reproduction : 



2. Zygospores formed in one filament AT. Antheridium o.Oogonium 



3. Germination of zygospore Spermatozoids 



4. Vaucheria sessilis, branched filament 8, 9, 10, 11, fol-vox globator. See text. 



with root processes 12 to 19. DESMID. Cosmarium botryth 



5 Asexual reproduction ; zoospore Propagation by division (Figs. 13 to 15) 



escaping Sexual reproduction (Figs. 16 to 19; 



6. Zoospore free 20. DESMID. Closterium lunula 



21. DIATOM. Tinnularia 'biridis 



