16 BOTANICAL GAZETTE [january 



much success bv F. N 



laboratory 



Periodicity of species studied 



m 



For the purpose of identifying the different species, the following 

 authors were consulted: Vaucher (6), Wood (9), Petit (5), and 

 Wolle (10). A brief account of the fruiting season of the different 

 species will be given below. 



Spirogyra infiata (Vaucher) Rab. — Vaucher reports this species 

 in fruit from February 20 to March 19. Petit gives April-May. 

 Unfortunately I was not able to find it except in a single locality. 

 This was in a small pond covering an area of perhaps iooo^- ft . The 

 surface was well covered with algae and floating debris of small sticks 

 and grass. This species was found floating on the water together 

 with S. catenae} or mis and 5. calospora. On May 2 all three species 

 were found in a state of conjugation interwined with each other. No 



2, although this pond 



iflata 



1 



summer 



Spirogyra quadrata (Hassall) P. Petit.— This is the Zygnema 

 quadratum of Hassall. Petit gives the fruiting season as April- 

 May. The writer studied this species in eight different localities, 

 varying from a few rods to twelve miles apart, but under no great 

 variety of conditions. In every case it was found in quiet surface- 



meadow 



middle of J 



were collected from among dead grass and leaves. S. quadrata was 

 found fruiting abundantly April 27, and within a week the eight 

 places mentioned above were visited and found in about the same 

 state of conjugation. By May 5 the Spirogyra at two localities had 



maximum 

 every case and no fruiting material 



found after May 19. The temperature of the water recorded at each 

 visit to the different ponds gave a range of 10-25 C. It was 



very 



filaments 



maximum 



Spirogyra calospora (Cleve).-WooD found this species fruiting 

 a ditch in a meadow late in April, and as late as May 25 in the 



