288 ZYGNEMATACEAE 



PLATE XXII 



Spirogyra 



Fig. I. — S. varians, gametangia, zygospores, and inflated sterile cell 

 from central Illinois. Fig. 2. — S. bicalyptrata, gametangia and zygospores 

 from Czechoslovakia. After Czurda. Fig. 3. — S. circumlineata, gametangia, 

 zygospores, and sterile cell from central Illinois. Fig. 4. — S. jennicu, lateral 

 and scalariform conjugation, and zygospores from Szechwan, China. After 

 Jao. Figs. 5-6. — S. parvula, scalariform and lateral conjugation, and an 

 aplanospore from central Illinois. Fig. 7. — S. supervarians, gametangia and 

 zygospores from Cape Town, South Africa. Fig. 8. — S. borgeana, gam- 

 etangia and zygospores from Illinois. (See also Fig. 16, PI. XXIII.) Fig. 9. 

 — S. subsalina, gametangia and zygospore from Finland. Figs, io-ii. — 5. 

 gibberosa, lateral and scalariform conjugation, separation of receptive gam- 

 etangia, and zygospores from Szechwan. After Jao. Fig. 12. — S. catenae- 

 jormis, scalariform and lateral conjugation, and sterile cell from central 

 Illinois. (See also Fig. 16, PI. XXIV.) Fig. 13. — S. bullata, zygospores, 

 gametangia, and sterile cells from Szechwan. After Jao. Figs. 14-18. — 5. 

 pratensis, vegetative cells, aplanosjwres, and zygospores. Note growth of 

 cells during development of aplanosporangia of which there are two extreme 

 types, also the bullate type of sterile cells. Type material from Charleston, 

 Illinois. 



