52 WEEVIL-RESISTING ADAPTATIONS OF COTTON. 



seemed unlikely in any case, because the unfertilized ovules were 

 already withering. 



Presumably there are various stages and degrees of fertilization. 

 Some of the stigmas of proliferated buds seem to have adequate 

 pollen, so that the bolls can develop normally, while others obtain 

 none at all or only a little. The persistence of injured flowers is 

 much greater. They may not fall off at all, and often remain at- 

 tached by the withered style to the boll when nearly full size. 



It thus happens that injured flowers protect their young bolls 

 longer than the others, but in most instances such bolls remain small 

 or unsymmetrical, presumably as a result of inadequate fertilization. 

 It is quite possible, however, for normal bolls to develop occasionally 

 from weevil-infested buds which never open, for the style often 

 pushes through and becomes fully exposed, so that fertilization by 

 pollen from another flower might readily take place. 



IMMUNITY OF VERY YOUNG BOLLS. 



For reasons not yet ascertained, the weevils in Guatemala seldom 

 or never attacked the very young bolls. This may be due to a con- 

 servative instinct on the part of the weevil, like that which forbids 

 the laying of any additional eggs in a bud already parasitized. It 

 is not impossible, however, that the oil glands with which the sur- 

 face of the young boll is very thickly beset may have a protective 

 function. As the boll grows larger the glands do not appear to 

 increase in numbers, but become separated much more widely. On 

 bolls of the Kekchi cotton the oil glands are usually absent from a 

 distinct longitudinal band running down the middle of each carpel. 

 (PL VII.) A large proportion of the. weevil egg punctures are 

 made along this naked band, although very few of them take effect. 

 The wall is thicker here, and the weevil in boring meets the tough 

 lining of the boll chamber at an angle, and is seldom able to penetrate. 

 If this interpretation of the facts be correct, the naked band consti- 

 tutes a veritable weevil trap, a device for inducing the weevil to 

 make its punctures and lay its eggs in the part of the boll where they 

 can do no harm. & 



To ascribe a protective value to the oil glands is not unreason- 

 able in view of the fact reported by Messrs. Quaintance and Brues, 



a Hunter. W. D.. and Hinds. W. E.. 1905. The Mexican Cotton Boll Weevil. 

 Bui. 51, Bureau of Entomology, U. S. Department of Agriculture, p. 78. 



b This peculiarity of a glandless longitudinal band in the middle of each 

 carpel was also noticed in a variety of cotton cultivated by the Moqui Indians 

 of Arizona, grown in 1904. in the Department's plant-breeding experimental 

 field at Terrell. Tex. The Moqui cotton is interesting also by reason of its 

 short, squarish, distinctly apiculate bolls, more like some of the Old World 

 cottons than are those of other members of the Upland series. 



