33 



in Minneapolis, and suggesting the possiljility that some other fac- 

 tor, such as Hght, may also be critical. 



Dr. Samuel G. Eddy of the Department of Zoology, University 

 of Minnesota, states that he has frequently observed macroscopically 

 similar communities in various other parts of Minnesota. 



Department of Botany, 

 North Carolina State College, 

 Raleigh, N. C. 



Algal Communities in Tully Lake 



Gkorge T. Hastings 



During a number of summers spent at Tully Lake, Onondaga 

 and Cortland Counties, N. Y., communities similar to those 

 described by Mrs. Buell were observed in August and notes and 

 drawings made. The lake has a maximum depth of about thirty 

 feet and has a soft white marl bottom. These floating colonies always 

 appeared in the deeper parts of the lake. Above the surface they 

 appeared as hemispheres 2 to 3 cm. across, below water extended 

 a skirt-like mass 7 to 10 cm. deep and about as much across. These 

 masses were made up chiefly of a species of Spirulina, the in- 

 dividual trichomes about 2 mm. long, with some species of 

 Oscillatoria, small colonies of Microcystis, various diatons and 

 protozoa. 



