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320
ZYGNEMATACEAE
PLATE XXXVIII
Spirogyra
Fig. I. S. licvcLinci, gametangia and zygospores troin S/.cchwan, C^hina.
After Jao. Fig. 2. S. areolata, gametangia and zygospore from central
Illinois. Fig. 3.— i'. tolosana, zygospores and gametangia from Indiana.
Fig. 4.-5. hcissaUii, lateral conjugation and zygospore from Szechwan,
China. After lao. Figs. 5-6. S. hartigii, scalariform and lateral conjuga-
tion, conjugating tubes, and zygospores. After Kiitzing. Fig. 7.—5. proarita,
lateral conjugation and tube. After Langer. Figs. 8-9. S. gratiana, straight
conjugating filaments, scalariform and lateral conjugation, zygospores, and
aplanospores. Fig. iu.— S. transeauiana, gametangia and zygospore from
Szechwan, China. After Jao. Figs. 11-12.—5. rectangulans, scalariform
and lateral conjugation with resulting zygospores from central Illinois.
Fig. 13. S. jallax, gametangia and zygospores from Bohemia. After Hans-
girg. Figs. 14-15. S. wangi, vegetative cell, gametangia, and zygospore
from Hangchow, China. After Li. Figs. 16-17. ^- acanthophora, gam-
etangia, zygospores, and details of spore wall from Latvia. After Skuja,
Figs. 18-20. S. inconstans, lateral and scalariform conjugation with result-
ing zygospores, and details of spore wall from Casey, Illinois. Note in
Fig. 19 an almost complete absence of the reticulum on the spore wall. This
depicts the extreme variation from Fig. 20.