246 



Journal New York Entomological Society. [VoI. xxiii, 



below the population percentage has been indicated by shading in the 

 area bounded by imaginary draughtsmen's curves smoothing the cal- 

 culated standard deviations about the general percentage line. The 

 chances are about 20 to i against purely random deviations falling 

 outside the shaded areas. 



Diagram i. Percentage of Seeds infested by Briichns in a Golden Wax 

 culture in general and in pods with various numbers of ovules. The general 

 percentage is shown by the central bar, that for the various pod classes by the 

 heavy dots on the ordinates for ovules. The shaded area gives the range of 

 twice the standard deviation of random sampling for samples of the size dealt 

 with. Note that all but one of the percentages for individual ovule classes 

 fall well outside this area. 



The diagrams show with great conclusiveness not only that the 

 percentage frequencies of parasitization actually observed in the indi- 

 vidual ovule classes differ from the average and that these percentages 

 increase from the lower to the higher ovule grades with considerable 

 regularity, but that for the most part the deviation of these percent- 



