EXTENT OB' PROTECTION BY INVOLUCRE. 41 



All example of the promptness with whieli weevil injuries cause 

 the involucres of our Uj^land cotton to open is well shown in a note 

 by Mr. McLachlan : 



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

 cotton, and 5 female and 2 male weevils were introduced. The plant i)ossessed. 

 ;!0 squares. 4 flowers, and bolls. The nutrninir after the weevils were imt 

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

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

 of the weevils. Here, of course, the imnctui-es were numerous, because of the 

 n)any weevils on the plant. Some of the sipiares were riddled witli 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 Avither up Avithout flaring. 



HAIRY MARGINS OF INVOLUCRAL BRACTS. 



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

 the marginal teeth or lacinitv 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 vei-y distinct 

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

 firmly appressed bracts of the Rabinal cotton have the maro-inal 

 lacinia' 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 or PROTECTION BY INVOLUCRE. 



That the closed involucres do indeed contribute to the protection of 

 the young buds from the weevils became very obvious in (me 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 



