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156
Czechoslovakia; Tibet; China.
ZYGNEMATACEAE
Figure 16 on Plate XXII I depicts an instance in which the terminal
cells of 2 adjacent filaments conjugated through the end walls with 2 adjoin-
ing receptive gametangia of a third filament. The specimen was collected
near Douglas Lake, Michigan. Named for the late Oskar F. A. Borge of
Stockholm, Sweden.
20. Spirogyra calcarea Transeau 1934. Trans. Amer. Micros.
Soc. 53, p. 226.
Vegetative cells 37-42 /x x 40-120/j., with plane end walls; i chromatophore,
making 2 to 5 turns in the cell; conjugation scalariform;
tubes formed by both gametangia; receptive gametangium inHated only
on the outer side; zygospores ellipsoid, 40-55 /a x 58-80 /a; median spore
wall smooth, yellow.
United States: Alabama, Birmingham, sinkholes in limestone.
Similar in form to S. borgeana but larger in all dimensions.
21. Spirogyra bullata Jao 1935. Sinensia. 6, p. 588, PI. 4, Fig. 55.
Vegetative cells 19-22/x x 41-83;", with plane end walls; i chromatophore,
making 1.5-5.5 turns in the cell; conjugation scalariform;
tubes formed by both gametangia; sterile cells buUate up to 64 m in
diameter and occurring in rows up to 25 cells long; fertile cells cylindric
or slightly enlarged; zygospores ellipsoid, 22-291". x 31-35 (-51)^; spore
wall smooth, yellow at maturity. (PI. XXII, Fig. 13.)
China, Szechwan.
Differs from S. pratensis in the shorter spores and absence of inflated
fertile cells.
22. Spirogyra pratensis Transeau 1914. Amer. Jour. Bot. 1,
p. 292.
Vegetative cells 17-20 /a x 80-240 jU, with plane end walls; i chromatophore
(rarely 2), making i to 8 turns; reproducing commonly by
both zygospores and aplanospores; conjugation scalariform and lateral;
tubes formed by both gametangia; fertile cells enlarged or fusiform-
inflated to 38 /ti; sterile cells cylindric or inflated up to 90 m in diameter;
spores in most cells ellipsoid, in others ovoid, or cylindric-ovoid,
2^-^6iJi X 50-70^1; median spore wall yellow, smooth. (PI. I, Fig. 7;
PI. XXII, Figs. 14-18.)
United States: Iowa; Wisconsin; Arkansas; Illinois; Michigan; Kentucky;
Ohio.
China, Peiping (Jao Coll.), Nanking (Li Coll.).
The occurrence of globoscly swollen sterile cells and the presence of
lateral and scalariform conjugation together with aplanospore formation in
most collections and sometimes in a single pair of filaments give character
to this species.