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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.