290 



zv(;nemataceae 



PLATE XXIir 



Spirogyra 



Fig. I. — S. fhivt'sccns, zygospores aiul gamctangia from Michigan. 

 Fig. 2. — S. subsalsa, gametangia and zygospore from Florida. Fig. 3. — S. 

 paludosa, gametangia and zygospores from Bohemia. After Czurda. Fig. 4. 

 — 5. mirabilis, zygospore (very rare) and aplanospore (the usual method of 

 reproduction) from Douglas Lake, Michigan. Fig. 5. — S. longata, zygo- 

 spores and gametangia from China. After Jao. The spores are not always 

 so long but are always ovoid. Fig. 6. — S. oltmannsii, aplanospores and 

 sporangia from South Africa. After Huber-Pestalozzi. Spores are "possibly 

 scrobiculate" when mature. Fig. 7. — S. suecica, gametangia and zygospores 

 from Sweden. After Borge. Fig. 8. — 5. gallica, gametangia and zygospores 

 from France. After Petit. Fig. 9. — S. porticalis, zygospores and gametangia 

 from Illinois. Fig. 10. — S. lacustris, gametangia, zygospore, and conjugating 

 tubes from Austria. Figs. 11-13. — S. lutetiana, various forms of zygospores 

 from France. After Petit. Figs. 14-15. — 5. polymorpha, zygospores, par- 

 thenospores, and variously shaped gametangia from China. After )ao. 

 Fig. 16. — S. borgeana, a remarkably rare instance of conjugation through 

 end walls of two filaments with two adjoining receptive gametangia of 

 another filament. Figs. 17-18.— 5. aplanospora, lateral conjugation and 

 aplanospore formation from India. After Randhawa. 



