7-4 WEEVIL-RESISTING ADAPTATION OF COTTON. 



ADAPTATIONS OF PACHON COTTON. 



1. Involucral bracts margined with stiff lacinise and bristles. 



2. Calyx large, the divisions slender and hairy. 



ADAPTATIONS OF SAN LUCAS SEA ISLAND COTTON. 



1. Definite seasonal bearing. 



2. Lint confined to outer half of seed. 



3. Proliferation in buds. 



4. Proliferation in bolls. 



ADAPTATIONS. OF KIDNEY COTTON. 



1. Definite seasonal bearing. 



2. Seeds compacted at center, covered with thick layer of lint. 



ADAPTATIONS OF UPLAND COTTON. 



1. Shedding of weevil-infested buds. 



This is the only weevil-resisting character in which the Upland varieties 

 excel the Kekchi cotton, but, as already explained, the habit is of practical use 

 only in dry climates. The Upland cottons share, however, a large number of 

 the adaptations, though in a le*s degree than in the Kekchi. Thus there is pro- 

 liferation both in buds and in bolls, the stems and petioles are somewhat hairy, 

 the habit of growth is somewhat reduced from the tree-cotton stage, the nec- 

 taries are often large and active, the involucral bracts are sometimes well 

 folded together, etc. 



And now that the possibility of weevil resistance has been shown, 

 variations may be found in all probability among our United States 

 varieties which will enable weevil-resisting strains of the Upland 

 >orts to be developed. At this stage of the inquiry it is too much to 

 hope that the Kekchi type will prove to be adapted to the wide 

 diversity of conditions to be found in the cotton belt. -Either the 

 Kekchi or the native cottons, or both, are likely to require extensive 

 modification before the full value of the weevil-resisting adaptations 

 can be realized. 



CONCLUDING REMARKS. 



The protection afforded by the weevil-resisting adaptations is 

 most effective at the two ends of the period of development, but con- 

 tinues in varying degrees from the young bud to the ripe boll. Under 

 favorable conditions an extremely small proportion of the weevil 

 eggs develop to maturity. Instead of a single attack being fatal to 

 a bud or boll, the same fruit at its different stages may resist numerous 

 punctures and egg-layings. The young bud is protected for a time 

 by the closed involucre. After the weevils have gained entrance the 

 first egg, and often the second or third, may be rendered harmless 

 through the proliferation of the bud in its younger stages. Pro- 

 liferation becomes less certain as the bud increases in size, but if egg 

 laying be delayed a few days too long the development of the larvae 



