Zygiiemacece 



133 



Fig. 49. A, Spirogyra nitida (Dillw.) Link, from near Morecambe, Lancashire; scala- 

 riform conjugation between six filaments ( x 75). B, S. setiformis (Both) Kiitz., 

 showing frustrated attempts at the conjugation of two male cells and one 

 female cell ( x 90). C, S. Spreeiana Rabenh., from near Esher, Surrey ( x 390). 

 D, S. inftata (Vauch.) Rabenh., from near Esher, Surrey; showing lateral 

 conjugation ( x 390). E and F, zygospores of S. velata Nordst., from Shipley 

 Glen, W. Yorks., germinating immediately after their formation and before the 

 differentiation of the wall of the zygospore ( x 165). G, germination of zygo- 

 spore of S. velata after normal period of rest ( x 230). 



