NOVEMBEE 18, 1904.] 



SCIENCE. 



667 



involucre had begun. The hairy stems 

 assist the ants in climbing, but impede the 

 weevils, and thus increase the chances of 

 capture. Prompt flowering and determin- 

 ate growth enable an annual variety to 

 ripen more seed. A perennial kidney cot- 

 ton also escapes extinction by producing 

 nearly all its blossoms at one season. In 

 the central plateau region of Salama and 

 Rabinal another perennial variety is cut 

 back annually to the ground. New shoots 

 spring up and the new crop is set within 

 a short time, while the plants are still small 

 enough to be cared for by the chickens and 

 turkeys. 



Another of these protective adaptations 

 proves to be of such potential significance 

 as to call for announcement in advance of 

 a detailed report. The issue is nothing less 

 than that the cotton plant, in some of its 

 varieties, has finally developed a practical 

 means of resisting and destroying the 

 weevil larvs. The process is in the nature 

 of a varietal characteristic subject to in- 

 crease by selection. The efficiency of the 

 adaptation is such that a variety in which 

 it appeared uniformly would afford no 

 opportunity for the weevil to breed, and 

 would thus be a means of exterminating it. 



The facts are simple and have been thor- 

 oughly established during the department's 

 entomological studies of the weevil for the 

 past decade, but they have not been inter- 

 preted as a protective adaptation, nor as a 

 character subject to further selective de- 

 velopment. Messrs. Hunter and Hinds 

 have reported* that in some instances as 

 high as 41 per cent, of the boll-weevil larvse 

 fail to develop, as a result of what they 

 have termed a 'gelatinization' of the tissues 

 of the young bud or 'square.' 



In the later stages the injured buds often 

 appear as though filled with a structureless 

 exudation, and it was not unnaturally sup- 



* Bull. 45, Bureau of Entomology, U. S. Dept. 

 Agriculture, p. 96, 1904. 



posed that the abnormality was the result 

 of some disturbance of nutrition, or of 

 bacterial infection. The material failed, 

 however, to yield cultures of bacteria or to 

 respond to experiments with fertilizers. 

 The opportunity of examining the earlier 

 stages of the phenomenon show that the 

 conditions are far less abnormal than have 

 been supposed, and that the 'gelatiniza- 

 tion' is simply the result of very active 

 growth or proliferation of the loose tissue 

 of the tube or column, which in the flowers 

 of the mallow family surrounds the style 

 and bears the stamens. 



The usual program would be for the 

 young squares to fall to the ground when 

 the larva has hatched and begun to eat out 

 the pollen of the young bud. Proliferation 

 involves the opposite procedure. Instead 

 of ceasing to develop, the soft tissues of 

 the staminal tube are stimulated in a man- 

 ner analogous to that by which galls and 

 other vegetable excrescences are formed. 

 The cavity eaten out by the larva is filled 

 and the little miscreant is either smothered 

 in paste or, more likely, starved by the 

 watery tissue which is certainly no equiva- 

 lent for the highly organized protoplasm 

 of the pollen, the normal infant-food of the 

 young larva. But whatever may be the 

 actual cause of death the practical fact is 

 that the larva is killed, and apparently in 

 every instance in which proliferation oc- 

 curs.* A very little of the new tissue may 

 be effective. "When the cavity eaten out 

 by the larva is small it is often neatly 

 plugged by the new growth, and the flower 

 may develop with no very great distortion, 

 though the corolla generally shrivels up 

 before reaching more than half the normal 

 length. The young boll is not always 



* In a few cases living weevil larvte were found 

 in squares which gave evidence of gelatinization, 

 but there was always a second puncture from the 

 outside, indicating that another egg had been de- 

 posited. 



