527 



where in Spoon River tables have little significance save as 

 they express relative quantities in catches of chronological 

 sequence. Thus, in this table differences in successive months 

 have more significance than those in the same month of differ- 

 ent years. 



COMPARISON OF MONTHLY MEANS OF PLANKTON PRODUCTION IN ILLINOIS AND 

 SPOON RIVERS, BASED ON COINCIDENT CATCHES.* 



^Amounts in this table are cubic centimeters of plankton per cubic meter of 

 w^ater after subtracting from the total catch the estimated amount of silt. 



A detailed comparison of the production of the two streams 

 by months has been made elsewhere (see pp. 340-350). For 

 the purposes of the present discussion it will suffice to call 

 attention to a few salient features found in the somewhat 

 irregular data of the table. 



In but few averages does the plankton in Spoon River 

 equal in amount that of the Illinois. Not only is this true 

 of the monthly averages with but three exceptions, but 



