20 



PROLIFERATION IN CONTROL OF BOLL WEEVIL. 



At the end of Table V are given totals and average percentages 

 for squares and for })olls, but the differentiation of the results for fer- 

 tilized and unfertilized plats is more clearly shown in Tal)le VI, which 

 is practically a summary of Table V. In each case the totals show 

 the amount of data upon which the conclusions rest. 



Tablk \'1. — Suminanj of data appearing in Table V , showing effect of fertilization upon 

 formation of proliferation, and the mortality of weevils in squares and bolls. 



« Weighted average. 



An examination of Table VI shoM^s that proliferation follows weevil 

 attack in approximatelj' two-thirds of the cases in bolls and in 

 approximately one-half of the cases in squares. As between squares 

 on fertilized and unfertilized plats, there is found a difference of only 

 1 per cent, wdiich is in favor of the fertilized plats. In the figures 

 for bolls there is shown a difference of 3.3 per cent in favor of the 

 unfertilized plats. Even if both these diflferences were on the same 

 side of the account, they are too small to justify the conclusion that 

 fertilization with acid phosphate, as used in these experiments, 

 appreciably affected the percentage of instances in which prolifera- 

 tion followed weevil attack. 



From a comparison of the mortality percentages it appears that, 

 although among the squares from fertilized plats there is a slightly 

 larger percentage of squares showing j^roliferation following weevil 

 attack, there is, on the contrary, a smaller difference in the average 

 mortality which may be attributed to the presence of proliferation 

 than is found among the squares from unfertilized plats. With 

 s(iuares on the unfertilized plats having a slightly smaller percentage 

 showing proliferation there is a somewhat higher average mortality 

 apparently due to the presence of proliferation. In a similar compari- 

 son with bolls, among those grown on fertilized ground showing pro- 

 liferation in 66.2 per cent of the injured locks, there was an average 

 increase of 9.4 in the percentage of mortalit}", while in bolls grown 

 on unfertilized ground showing proliferation in 69.5 per cent of 

 injured locks the average excess of mortality apparently due to 

 proliferation is only 8.1 per cent. 



