SPIKOG YRA. 



II 9 



Synopsis. 



Vegetative stage ; single unbranched threads, composed of 

 cylindrical cells end to end. 

 Cells all alike. 



Grows by division and elongation of all the cells. 

 Spirogyra. -j s exua l stage ; conjugation of like cells. 



Receiving and supplying cells, not differentiated. 

 Result of conjugation, a zygospore. 

 The zygospore after a period of rest produces the spirogyra 

 thread again. 



Material. — Spirogyra in conjugation, showing different stages, as well as 

 the zygospores. The material may be collected fresh, or it may be preserved 

 in 2% formalin collected in advance or purchased from supply companies. 

 Microscope, etc. 



