SEEDS OF BOLIVIAN MAIZE 



The group at the left is made up of self colored seeds infested by the larvae of the Angoumois 

 moth, whose tracks are conspicuous on the seeds. The group at the right has not been 

 attacked by this larva, but the mottled coloring resembles the tracks of the larvae. It 

 seems possible that this mottling may deceive the larv^ae; they "think" that the seeds 

 have already been entered and therefore pass on to find fresh fields. Photograph natural 

 size. (Fig. 1.) 



Table I. — Percentage of Non-infested, Single-infested and Double-infested Seeds Compared iinth the 



Expected Percentage* 



* I am indebted to Dr. Sewall Wright for suggesting the method used to determine the ex- 

 pected number of double-infested seeds. 



The formula for calculating the expected percentage of uninfested seeds is — —- and for 



I ^ J 

 fiV-iU-i fll 

 the percentage of single-infested the formula is . . . L\ — — — ■ — where .V= the total 



total number of seeds and L = the number of larvae. The remainder, of course, equals the 

 number of seeds infested with one or more larvae. 



of infestation on a mottled ear, also 

 affords a measure of the effectiveness of 

 the mottled aleurone as a protection. 

 Since all the seeds of a mottled ear 

 have the appearance of being infested 



the percentage of seeds actually in- 

 fested should approximate the per- 

 centage of double-infested seeds on a 

 self-colored ear having all the seeds 

 infested by at least one larva. These 



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