262 REPRODUCTION, EVOLUTION, ETC. 



SCHEME A 



CHLAMYDOMONADACEAE 



(motile) 



y 

 Spherical / Chlorococcum 



colonies / (non-motile, free-living) 



Pandorina 



/. 



Eudorinn 



\ 



Gelatinous 



colonies 

 Palmellaceae 



Dendroid colonies 



Characium (non-motile, Enlarged unicell 

 attached unicell) \^ ? (Protosip/wti) 



Ulothrix- 



Hydrodictyon ^, 



(net'i (simple filament^ ^ 



Cylindrocapsa ^k^/ isogamy) \ MicTospora 



->ConjugaIes 



Charales 



Siphonocladiales^? 



(Dioecious).] Tribonerna 

 ' (Hetero- 



trichales) 



Pleodorina 



\ 



Volvox ^g^ -^ , 



Monostroma Schizomeris ^ / 

 Ulvales-^^ ' Oedogoniales ^ 



\ 



Prastola 



? 



Bangia Stigeoclonium 



(Heterotrichy, isogamy) Siphonales 



V ^ ^ 



? ? ,Coleochaete Trentepohlia Protoderma Draparnaldia 



(oogamy) ? (reduced, (reduced, 



., base only) aerial only) 

 Eu-florideae Phaeophyceae 



The names of the genera do not necessarily imply that they 

 formed the actual intermediate stages, but merely that forms like 

 them existed in the evolutionary sequence. 



SCHEME B 



PALMELLACEAE 



Charales 



Ulvales 



Schizogoniales 



Hormidium 



\ 



Ulothrix 



Stigeoclonium 



Coleochaete 



Volvocales 



Chlamydomonadaceae 

 Protosjphon 



i 



Siphonales 



Pleiirococcus (reduced type) 



Siphonocladiales 



The Chaetophorales are represented as derived either from the 

 Ulotrichales (A) or from the Palmellaceae (B), but Vischer has 



