IOWA ACADEMY OF SCIENCE 53 



JIEASIREMEXTS FOR WIDTH OF POLLEN GRAIN. 



Magnitudes 20^, 24/^, 28^, 32m, 36/tt, 40ai 



Frequencies 1, 23, 238, 594, 164, 8 



The width as shown, varied from 207r — 40/x. with the mode at 327r. 



JIEASURE^IENTS FOR LENGTH OF POLLEN GRAIN. 



Magnitudes 28^. 32/x. 36^, 40^, 44ai, 48m, 52m, 56m, 60m, 64m, 68m 



Frequencies 1, 1, 2, 1, 2, 14, 161, 548, 283, 14, 1 



The length varied from 28m to 68m, with the mode at 56m. 



CONSTANTS FOR MEASURE:\IENTS OF WIDTH OF POLLEN GRAIN. 



n=1024. Ea=.2448. 



A=31.7068. E5=.1731. 



5=11.6156. Ec=.6119. 

 0=36.634%. 



CONSTANTS FOR MEASUREMENTS OF LENGTH OF POLLEN GRAIN. 



n=1024. Ea=.27052. 



A=56.1328. E5=.198. 



5=13.32. Ec=.3727. 



0=23.729. 



The average size was found to be 31. 7m by 56.29m. 



Both curves exliibit the more abrupt side in the direction of greater 

 dimensions; the tendency therefore, so far as indicated by this study, 

 is toward greater width and length of pollen grains. 



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