NANNOPLANKTON OF LAKE MENDOTA 91 



Explanation of the Nannoplankton Diagrams 



Figures 32 and 33 show the numerical results obtained for the samples 

 of nannoplankton from Lake Mendota; the spherical type of curve 

 has been used. The curves show the number of individuals or colonies 

 in 10 liters of water. In order to bring out the variations in the quantity 

 of organic matter more clearly by this type of diagram, that curve was 

 platted on a different scale; it shows the number of milligrams of dry 

 organic matter in 10,000 cubic meters of water. 



The following abbreviations have been used for the different organ- 

 isms: RH=Rhizopoda, CH=Chlorochromonas, CR=Cryptomonas, 

 EU— Euglena, CI=Ciliates, AP=Aphanocapsa, AR=Arthrospira, CC 

 =Chroococcus, CL=Closterium, CO=Coelosphaerium, CM=Cosma- 

 rium, 00=Oocystis, SC=Scenedesmus, SP=Sphaerocystis, CS=Coc- 

 coneis, CY=Cyclotella, SA=Stephanodiscus astraea, ST=Stephano- 

 discus, OM— organic matter, FD=fragments of diatoms, FA— frag- 

 ments of Aphanizomenon. 



