58 WEEVIL-RESISTING ADAPTATIONS OF COTTON. 



growth and do not appear to hatch, or if they do the larvte are not 

 able to do any damage, since they can not penetrate into the interior 

 of the boll. It quite frecjuently happens that eggs are laid in the 

 sinns or groove between the linings of two locks, but without penetrat- 

 ing the parchment of either. The tissue is here somewhat looser 

 than in other parts of the wall. In a few instances it was observed 

 that the larvge had hatched, but no case was found which indicated 

 that larvae hatched outside the parchment lining had been able to 

 penetrate to the interior cavity. 



PROLIFERATION rRO:M THE WALL OF THE BOLL. 



The wall of the boll olfers an active form of weevil resistance Jw 

 proliferation, in a manner somewhat analogous to that of the pro- 

 liferation of the square. The channel excavated by the weevil is 

 closed by the new growth, which continues to push out on the inner 

 surface of the wall in the form of a rounded, blister-like protuber- 

 ance of loose tissue. This surrounds and encysts the weevil egg, and 

 prevents its development. A section through the mass of new tissue 

 shows the egg embedded in it or pressed against the lint. Prolifera- 

 tion often takes place even when the tough lining of the chamber has 

 not been penetrated, and then appears as a prominence underneath 

 the membrane. 



It has been seen from the preceding paragraph describing the 

 thick walls and tough lining that in the Kekchi cotton, at least, 

 the weevil is practically excluded from the boll after the boll has 

 reached about three-quarters of its full size ; but even in its younger 

 stages also there is a measure of defense through the formation of 

 new tissue as a result of the irritation set up by the weevil's injuries 

 in a manner analogous to that which induces the formation of galls 

 and other vegetable excrescences. 



The first result of the proliferation is to fill up and heal the 

 wound bored out by the weevil. The cavity is not only completely 

 filled, but in most cases a wartlike prominence is formed on the out- 

 side, and if the parchment lining or the inner wall has been pene- 

 trated the new proliferating tissue also grows through on the inside 

 and often spreads out as a biscuit or button shaped protuberance 

 of soft white or transparent tissue several millimeters in diameter 

 and readily visible to the naked eye. (PL VIII.) 



There are two alternatives in the fate of an egg destroyed by 

 proliferation. Either it is completely surrounded in the proliferating 

 tissue outside or inside of the parciiment wall or it is carried on 

 the apex of the proliferation down against the lint and flattened 

 between the growing surfaces. After the egg has disintegrated 

 and disappeared its position is frequently shown by a minute brown 



J 



