1909] COPELAND— PERIODICITY IN SPIROGYRA 17 



"neck' 5 below Philadelphia, The season given by Petit is April- 

 May, and the habitat "ditches in low ground and swamps." For 

 this species the present paper includes notes from observations of 

 five different ponds and one brook in different localities, and includ- 

 ing a greater variety of conditions than those described for S. quad- 



rat a . ■ 



growm 



and continued in increasing abundance until about the second week 

 in May. In two of the ponds the disappearance was by no means 



rapid. 



May 6 and the last 



June 4. The average temperature was 7-1 4 C. In the pond in 

 which most fruiting material was found the temperature ranged from 

 7 to 1 1° C at the time of maximum conjugation. 



Spirogyra Hantzschii Rab. — In 1906 fruiting material was col- 

 lected first on April 28, and, with one exception, no fruiting material 

 was gathered after May 23. In the fall of 1905 this species was found 

 in active vegetative condition in three localities. Examinations were 

 made frequently during the fall and, when the ponds were free from 

 ice, during the winter. This species lived beneath the ice and in two 



come 



of conjugation, but was collected from the debris at the bottom of the 

 ponds. Temperature of the water varied from i2-28°C. There 

 was no great range of habitat; generally in shallow ponds near the 



dav 



more or less protected from 



sun. 



Spirogyra mirabilis (Hassall) .— This species is described by 

 Hassall and also by Petit as producing spores without conjugation 

 and by no other method. Wolle states that lateral conjugation is 

 more frequent than scalariform. I was not able to find this species 

 in fruit in the pond from which this material was taken. It was 

 brought into the laboratory in the vegetative condition April 2 and 



5 



formed 



scalariform 



aquaria. On May 7 



all other spores 

 n nlace. Corn- 



formed spores and very 

 July as the fruiting sea 



In the material 



-cmionea ail fruiting specimens 

 b y the second week in June. 



