190 



PLANKTON OF WISCONSIN LAKES 



Table 14. A summary of the ash and silica determinations for the 

 net plankton of Lake Mendota, 1911 to 1917. The results are stated in 

 percentages of the dry weight of the net plankton. 



Year 



Number 

 of 



Samples 



Per Cent of Ash 



Per Cent of Silica 



Difference 



between 



Means of 



Ash and 



Silica 



Maxi- 

 mum 



Mini- 

 mum 



Mean 



Maxi- 

 mum 



Mini- 

 mum 



Mean 



1911 

 1912 

 1913 

 1914 

 1915 

 1916 

 1917 



22 

 29 

 35 

 14 

 34 

 39 

 11 



40.67 

 38.30 

 43.78 

 13.63 

 48.30 

 45.18 

 46.66 



7.54 



5.62 



10.08 



9.13 



9.40 



16.56 



13.40 



17.65 

 19.47 

 22.70 

 11.56 

 29.09 

 29.07 

 27.44 



32.66 

 31.62 

 36.42 

 9.04 

 37.25 

 36.86 

 21.32 



1.97 

 0.76 

 0.50 

 1.34 



2.84 

 2.80 

 3.79 



9.22 

 12.37 

 14.45 



3.84 

 17.37 

 15.55 

 10.04 



8.43 

 7.10 

 8.25 

 .7.72 

 11.72 

 13.52 

 17.40 



Table 15. Analyses of the ash of the net plankton. The results are 

 stated in percentages of the dry weight of the net plankton. 





Number 







Fe 2 3 + 











Lake 



of 



Sample 



Ash 



Si0 2 



AI2O3 



Mn 3 4 



P 2 5 



CaO 



MgO 



Mendota . 



102 



12.25 



2.41 



2.18 



0.00 



2.08 



3.60 



0.20 





108 

 112 



19.87 

 12.53 



10.36 

 2.90 









3.83 

 6.18 



1.95 





0.98 





2.12 



0.62 





116 



28.38 



21.50 



1.12 



0.00 



1.43 



2.97 



0.51 





117 

 118 



40.67 

 12.25 



32.66 

 4.92 



1.20 



"o!oo' 



1.42 

 1.82 









2.75 



0.86 





125 



15.30 



8.94 



0.67 



0.00 



0.59 



2.68 



0.17 





130 



24.40 



16.93 



1.44 



0.00 



1.17 



3.29 



0.40 





202 



17.82 



6.74 



0.26 





0.25 



4.36 



O.SO 





207 



9.90 



3.45 



1.02 





1.58 



2.23 



0.24 





213 



12.98 



1.63 



0.83 





0.94 



6.80 



0.23 





220 



5.62 



1.38 



0.84 





0.76 



1.63 



0.35 





302 



19.56 



12.58 



1.00 





2.00 



1.60 



1.04 





307 



22.82 



15.57 



1.17 





1.78 



2.65 



1.16 





311 



13.32 



1.56 



0.67 





2.54 



5.43 



1.41 





325 



11.01 



6.06 



0.45 





1.48 



1.03 



1.24 





337 



19.72 



9.10 



0.68 





2.31 



3.72 



0.74 





350 



33.60 



25.58 



0.88 





1.45 



2.50 



0.87 





359 

 363 



29.86 

 21.21 



18.66 

 7.86 









4.75 

 2.01 



0.94 







0.34 





0.90 





366 

 367 



30.99 

 33.35 



20.74 

 25.36 









4.01 



0.82 







0.38 



1.22 







401 



9.64 



2.40 





0.31 



0.58 



1.37 



1.03 





404 

 409 

 502 

 503 

 330 



13.63 



9.13 



24.72 



19.65 



6.20 



5.14 



3.86 



10.76 



11.12 



0.38 





0.30 

 0.39 



1.30 

 1.40 















2.98 

 1.37 

 1.56 



1.53 











0.71 



Monona. . 



0.40 





1.28 



0.81 





354 



12.16 



4.71 



1.32 





0.83 



1.70 



0.20 



