40 



WEEVIL-RESISTING ADAPTATIONS OP COTTON. 



To show the increased, size of the bracts in the Kekchi cotton. I have carefully 

 measured over 250 squares of five of the most promising varieties of the Upland 

 species. The dimensions taken were the length of the floral bud, and the length 

 and breadth of the bracts. The table, in which these data are condensed in a 

 comprehensive form, shows a decided advantage in favor of the Kekchi cotton. 



Table I. — Dimensions of floral buds and bracts of several varieties of cotton 



compared. 



Length of 



floral bud 



(millimeters). 



Kekchi. 



Parker. 



King 





Allen. 



Jewett. 



o 



P 



o 



A O 



tfr " 



<s 



mm. 

 20 

 28 

 39 

 42 

 42 

 42 

 47 

 52 

 37 

 47 

 42 



$a 

 pq 



mm. 

 11 

 18 

 27 

 30 

 30 

 30 

 33 

 30 

 27 

 36 

 30 



2 . 



* 



o 

 At 



o 

 A-v 



pq 



S4-I 



o 



o 

 At 



o 



-~ •_ 



ffl 



o 



o 



A o 



r, - 



it Ph 



<D 



o 

 A+S 



T. i-t 



<pA 



o 



M 



O 



GA 



o 

 A+Z 



*.& 



f-l 



pq 



5- 6. 



1 

 1 

 6 

 5 

 3 

 4 

 3 

 2 

 1 

 3 

 2 



mm. 



mm. 





mm. 



mm. 



mm. 



mm. 





mm. 



mm. 



7- 8... 



2 



13 

 16 



18 

 8 



I 



3 



1 

 3 

 2 

 2 



1 



25 

 31 

 36 

 39 

 38 

 39 

 43 

 48 

 36 

 37 

 44 

 45 

 47 



19 



20 

 24 

 25 

 23 

 26 

 24 

 26 

 25 

 25 

 25 

 24 

 30 







"19 

 23 



24 

 25 

 24 

 26 

 25 

 26 



1 



18 



10 



18 



13 



5 



1 



1 



5 



1 



5 



26 

 34 

 34 

 37 

 39 

 39 

 49 

 40 

 40 

 32 

 42 



20 

 21 

 22 

 23 

 24 

 25 

 29 

 26 

 23 

 21 

 25 









9-10 



5 



7 

 9 

 6 

 6 

 4 

 1 

 2 



33 



34 

 40 

 44 

 40 

 42 

 43 

 41 



3 



2 



10 

 7 

 5 

 1 

 2 



38 

 36 

 39 

 41 

 39 

 52 

 47 



26 

 21 

 26 

 28 

 530 

 38 

 34 



11-12 



13-14 



15-16 . 



17-18 



19-20.. 



21-22 



23-24.. 



25-26... 



1 



48 



33 



27-28 



2 



1 



40 



49 



25 



28 



29-30 

















31-32... 





















33-34 





















1 



42 



32 



Total.. 









78 











43 







78 







31 



32 























The advantage is particularly notable with respect to the greater 

 width of the bracts, which enables them to remain much more effect- 

 ively closed at the angles. In the Parker, King, and Allen varieties 

 the bracts very seldom attain a width of 30 mm., while in the Kekchi 

 cotton the average width for all except the smallest buds is above 

 30 mm. 



OPENING, OR FLARING, OF BRACTS AVOIDED. 



The unusually large and well-closed bracts of the Kekchi cotton 

 have another practical use in keeping the bud from drying out, as 

 explained in the discussion of proliferation. 



The external indication of this difference is that in the Kekchi 

 cotton punctured squares commonly do not open, or flare, by the 

 spreading apart of the involucral bracts, while among the Upland 

 and Sea Island varieties flaring is the regular rule. Quite a per- 

 centage of the squares of Abbasi, Parker, King, and other varieties 

 stand well open normally before any injury has occurred, but the 

 Kekchi cotton seldom or never exposes its squares before flowering. 

 The larger and broader involucre is also able to permit the protrusion 

 of the flow T er without losing the power of closing and remaining 

 shut for a considerable period after flowering, while the Parker and 

 King varieties often remain quite open, so that the young boll is 

 fully exposed to the w 7 eevils. 



