EXTENT OF PKOTECTION BY INVOLUCBE. 41 



All example of the promptness with which weevil injuries cause 

 the involucres of our Upland cotton to open is well shown in a note 

 by Mr. McLachlan : 



On August 8, at 2 p. m., a small cage was placed over a small plant of Parker 

 cotton, and 5 female and 2 male weevils were introduced. The plant possessed 

 36 squares, 4 flowers, and 9 bolls. The morning after the weevils were put 

 into the cage several of the squares had flared and one had fallen. It would 

 seem that the mechanical forces of the square are quickly affected by the work 

 of the weevils. Here, of course, the punctures were numerous, because of the 

 many weevils on the plant. Some of the squares were riddled with feeding 

 and egg punctures. 



The buds of Kekchi cotton often recover from three or four punc- 

 tures, though they might not do so if these were all made at the same 

 time. But it often happens that squares with numerous feeding 

 punctures remain closed and wither up without flaring. 



HAIRY MARGINS OF INVOLUCRAL BRACTS. 



In addition to their larger size, the bracts of the Kekchi cotton have 

 the marginal teeth or lacinise more numerous and more hairy than 

 those of our Upland varieties and able to afford more of an impedi- 

 ment to the entrance of the weevils. The difference was very pro- 

 nounced in our experimental plot, where King, Parker, and other 

 familiar American sorts were planted beside the Kekchi. It is as 

 superior in this respect to the other Upland varieties as they are to 

 the Sea Island. 



The Kekchi and Rabinal varieties, though both belonging to the 

 Upland series and having many similarities, have also very distinct 

 differences, as, for example, in the present character. The small, 

 firmly appressed bracts of the Rabinal cotton have the marginal 

 lacinise few and small; sometimes the edges are nearly entire, or 

 merely toothed. The hairy covering is also reduced to a fine, short 

 coat, which can afford little or no impediment to the weevils. 



EXTENT OF PROTECTION BY INVOLUCRE. 



That the closed involucres do indeed contribute to the protection of 

 the young buds from the weevils became very obvious in one of our 

 experimental plots at Secanquim, located about a quarter of a mile 

 outside the belt of Indian cultivation of cotton. There being no 

 keleps to afford protection, the cotton soon became thickly infested 

 with weevils, and very few bolls were allowed to develop on any of 

 the plants. There was a notable difference, however, in the age at 

 which the buds were punctured. As already stated, the edges of the 

 bracts of some of the Sea Island and Egyptian varieties separate at 

 a much earlier period than those of the Upland varieties, and the 



