300 



250- 



200 



(0 



O 



UJ 



_J I 50- 



or 



UJ 

 0_ 



CO 



UJ 

 O 



I 00- 



BIOTIC INFLUENCES ON PLANKTONIC ALGAE 



T 



231 



x 



o. 







- 9 



- 8 



- 7 



- 6 



12 3 4 5 6 



TIME IN DAYS 



Figure 3. — Growth curve of Nitzschia in standard culture medium. Dots represent growth curve of Nitzschia ; circles, 



phosphorus concentration ; triangles, pH. 



