CONTENTS. 



Page. 



Introduction 7 



Selective influence of the boll weevil 10 



General protective characters : 11 



Dwarf habit and determinate growth of Kekchi cotton 11 



Variations in the Kekchi cotton 15 



Effects of Guatemalan conditions on United States varieties. 17 



Acclimatization of Kekchi cotton in the United States 17 



Early bearing facilitated by long basal branches 19 



Early rejection of superfluous squares 20 



Seasonal bearing of perennial varieties 23 



Annual cutting back of perennial varieties 24 



Hairy stalks and leaf stems 25 



Pendent bolls . , 27 



Extrafloral nectaries 28 



Nectaries of the leaves 30 



External nectaries of the involucre - 31 



Inner nectaries of the involucre _ _ _ 31 



Nectaries of Guatemalan Sea Island cotton 32 



Continued secretion of nectar 32 



Bractlets subtending inner nectaries 33 



Efficiency of the kelep protection 34 



Other nectar-bearing plants visited by the keleps 36 



The involucre as a protective structure 37 



Involucral bracts grown together 37 



Appressed margins of bracts . 38 



Large involucres of Kekchi cotton 39 



Opening, or flaring, of bracts avoided 40 



Hairy margins of involucral bracts - . 41 



Extent of protection by involucre 41 



Advantage of open involucres _ 42 



Behavior of parasitized buds 43 



Shedding of weevil-infested squares ... 43 . 



Countings of flared and fallen squares 45 



Proliferation of internal tissues of buds 46 



Causes and conditions of bud proliferation 49 



Proliferation in other varieties 50 



Protection of the bolls 51 



Persistence of flowers 51 



Immunity of very young bolls 52 



Rapid growth of young bolls _ 55 



Thick- walled bolls 56 



Tough linings of chambers of bolls . 56 



5 



