60 WEEVIL-RESISTING ADAPTATIONS OF COTTON. 



or enter the square late and develop very promptly. The insect has 

 been able, as we know, to avail itself with a large measure of success 

 of both these alternatives, but it is not without encouragement for 

 future progress in weevil resistance to know that the plant has so 

 successfully guarded itself in two parts of its life history. 



If additional evidence be needed to show that the food supply 

 obtained by the weevil larva? in the bolls is very different from that 

 in the squares, it is to be found in the large, firm-walled cells of com- 

 pacted excrement with which they surround themselves in the bolls 

 before reaching maturity. The food being of a much coarser nature 

 and the period of development about three times as long, the amount 

 of waste material is naturally very much greater. If feeding upon 

 the boll is, as now appears probable, the ancestral habit of the wee- 

 vil, it need not surprise us that the protective adaptations of the boll 

 are more numerous and effective than those of the bud, which may 

 have been attacked b} r the weevil in comparatively recent times. 



TIME REQUIRED FOR PROLIFERATION. 



In connection with the experiments in Texas, Mr. McLachlan at- 

 tempted to ascertain the time required for proliferation to take place 

 after the injury had been inflicted. The amount of proliferation 

 and the time required for it to develop may be expected to depend 

 much on external conditions. Squares of Parker cotton showed no 

 development in six hours, but observation on bolls showed that pro- 

 liferation was complete in twenty-four hours. Two of Mr. McLach- 

 lan's observations are described in the following notes : 



On August 14, at 9.15 a. m. 3 a wire cage was placed over a plant of King 

 cotton, and four weevils, of which at least two were females, were put inside. 

 Later, three more were introduced. At the time there were 11 bolls, 39 square*. 

 and 1 flower on the plant. 



On August 17. at 1 p. in., 11 bolls and 18 squares were picked, a little more 

 than three days being allowed for the weevils to work. There was no rain, and 

 of the 18 squares examined only one revealed proliferated tissue, though the 

 weevils had scarred the buds in more than 33 separate places and had deposited 15 

 eggs. But the bolls showed better results. They had been scarred at 32 different 

 points, and 23 eggs were discovered when the bolls were cut open. In 12 oases 

 inward proliferation of the " shuck " had destroyed the eggs. Several of the 

 incited growths had caught the egg, encysted it, and carried it along, inclosed 

 at the apex, as they pushed their way into the lint. As in the Parker cotton 

 examined a short time ago, weevils seem to have some difficulty in getting 

 the egg through the shuck of the boll. In dry weather it appears that the 

 King cotton is as backward as the Parker in proliferation in the squares, but 

 in bolls proliferation goes forward as well in dry as in wet weather. 



On the 30th of August, at 10.15 a. m., a boll (half grown and tender) was 

 bagged with a weevil. At 6 p. m. of the same day an egg puncture was found 

 on the fruit, but at 8 a. m. of the 31st no further injury had been inflicted. At 

 12 in., September 1, four more egg punctures were discovered, and the boll was 



