561 



sis, production in Phelps and Flag lakes exceeds that reported 

 in any other body of water save only from the shoaler part of 

 Turkey Lake (Juday, '97). This greater production in Turkey 

 Lake disappears if centrifuge measurements are employed in both 

 planktons, the ratios being 203.52 and 224.48 cm.^ for Flag and 

 Phelps lakes to 136.8 and 27.1 cm.^ for Turkey Lake. The ten- 

 dency on the part of this maximum production in all of the lo- 

 calities to fall in either the April-May period or in that of 

 August-September is apparent, though in some cases, as, for 

 example, those of Lakes Michigan and St.Clair, and Turkey 

 Lake, the limitation of collections to a few weeks in midsum- 

 mer precludes the possibility of a vernal pulse appearing in 

 their records. 



