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. 



