Summary of adaptations. 73 



ADAPTATIONS TO EXCLUDE WEEVILS. 



1. Involucral bracts grown together at base. 



2. Closely appressed margins of involucral bracts. 



3. Margins of involucral bracts strongly laciniate and hairy. 



4. Unusual size and width of involucral bracts. 



5. Calyx produced into slender hairy lacinise. 

 <">. Persistent flowers. 



7. Oil glands (?) of very young bolls. 



8. Thick-walled bolls. 



0. Tough linings of boll chambers. 



ADAPTATIONS ATTRACTIVE TO THE KELEP. 



1. Nectaries of leaves. 



2. Large outer nectaries of involucre. 



3. Large inner nectaries of involucre. 



4. Bractlets subtending inner nectaries. 



5. Continued secretion of nectar. 



6. Hairy stalks and leaf steins. 



7. Dwarf, compact habits of growth. 



ADAPTATIONS TO PREVENT DEVELOPMENT OF WEEVIL LARV.E. 



1. Shedding of weevil-infested buds. 



2. Proliferation of internal tissues of buds. 



3. Proliferation from the walls of the bolls. 



4. Absence of oil glands over dissepiments. 



5. Growth of lint on seed. 



6. Compacted Feeds (Kidney cotton). 



7. Lint confined to outer end of seed ( San Lucas Sea Island cotton ) . 



ADAPTIVE CHARACTERS OF DIFFERENT TYPES OF COTTON. 



The third standpoint for viewing the adaptive characters is that 

 of the different types of cotton. All varieties share, to some extent, 

 the older adaptive features, but the special characters are accentuated 

 in different degrees in the various types. Our study has been directed 

 toward the Kekchi variety, both on account of its relation to the 

 keleps and because it has seemed to possess by far the largest series 

 of adaptive features. But now that the existence of adaptations of 

 practical value has been ascertained it will be necessary to canvass 

 the field thoroughly. 



ADAPTATIONS OF KEKCHI COTTON. 



An enumeration of the adaptations of the Kekchi cotton is scarcely necessary, 

 because that variety has nearly the whole series and most of them in a more 

 accentuated form than the other types thus far studied. The few exceptions 

 are noted below. 



ADAPTATIONS OF RABIN AL COTTON. 



1. Prompt bearing after cutting back. 



2. Very hairy stalks, leaf stems, find involucral bracts. 



3. Closely appressed margins of involucral bracts. 



4. Involucral bracts grown together at base. 



