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SCIENCE 



[N. S. Vol. XXXII. No. 824 



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DiAGEAU 2. Showing change in radial asymmetry due to selective elimination for 

 each of twenty-eight individuals. 



the differences in asymmetry between largest 



and smallest are: 



Average asymmetry of 6-10 mm. ovaries 



= .382 ± .016 

 Average asymmetry of 16-20 mm. ovaries 



= .302 ±.013 

 Reduction in asymmetry by selective elimination 



= .0^ ± .020 

 This result, a decrease of 20.9 per cent, in 

 asymmetry, agrees with the preceding, but 

 owing to the smallness of the series the prob- 

 able errors are relatively large. 



The differences in the eliminated and ma- 

 tured ovaries appear in the frequencies of the 

 individual asymmetry classes. Grouping to- 

 gether the relatively few asymmetries of 

 l.SiTB and over, reducing the frequencies of 

 both eliminated and matured ovaries to a 

 percentage basis, we obtain diagrams 3 and 

 4. Here the areas with horizontal shading 



represent the frequency of eliminated ovaries 

 or of the youngest ovaries, while the vertical 

 shading shows the frequency of matured 

 fruits or of the most mature fruits for each 

 of the five asymmetry classes. 



The conclusions to be drawn are as obvious 

 as in the case of the mean number of ovules. 

 The failure of pods to complete their develop- 

 ment is not a matter of chance, but there is a 

 selective elimination in which the propor- 

 tion of radially asymmetrical fruits is very 

 greatly reduced. The ovaries which survive 

 to maturity are much more symmetrical than 

 those which are unable to complete their de- 

 velopment. 



Changes in Locular Composition due to 

 Selective Elimination. — The number of 

 ovules in Staphylea varies from about four to 

 about thirteen. Locules with numbers such 



