48 



PROBLEMS OP LAKE BIOLOGY 



Kio ifio 3oe 



MGTEKS 



STATICH-OH AlEXAHDER 



Fig. 1. 



Fig. 2 shows the location of stations where signifieant variations in the vertical distri- 

 observations were made. bution. Thns Kleiber (1894) failed to ob- 



serve any differences in numbers of bacteria 

 Vertical Distribution of Bacteria ^^ different levels in Lake Zurich. Pfen- 



Most studies of lake bacteria based upon niger (1902), working on the same lake, 

 culture methods have failed to show any found during summer stagnation that bac- 



