COTTON STRUCTURE 265 



appear, serve to nourish the plant before the appearance of true 

 leaves. 



240. Stages in the life of flower and fruit. When the 

 plant is about 40 days old, the first squares or flower buds 

 may usually be seen. If planting is done in hot weather, 

 the squares mature more quickly. Mercier reports that 

 21 days is the time from the first appearance of the square 

 to the opening of the bloom. From the open bloom to the 

 open boll the time varies according to the season of year 

 and the variety. As a rule in very hot weather, 42 days is 

 sufficient; while in the cooler weather of the early fall, 50 or 

 more days may be required. Therefore, blooms appearing 

 50 days before the average date of frost in a given locality 

 may be expected, under average weather conditions, to 

 mature. 



LABORATORY EXERCISES 



(1) Tie a string to the lowest branch of a well-grown cotton 

 plant and wind it spirally around the plant, in such a way as to 

 touch the base of each branch. By repeating this on several 

 plants determine the number of the branch from the bottom that 

 is directly above the lowest branch. 



(2) Make a record of how many times the string passes en- 

 tirely around the stem in being wound spirally from the lowest 

 branch to the one directly over it. 



(3) Compare, as to earliness of maturing, several plants with 

 long internodes on main stem and branches with others of the 

 same variety having short intervals between limbs or leaves. 



(4) Weigh the mass of seed cotton from 50 bolls each having 

 5 locks, and that from 50 4-lock bolls ; record and compare the 

 weights. 



(5) Find 5 storm-resistant bolls or old burs, and write down the 

 apparent reasons for the storm resistance of each. 



(6) Pull and break a small number of fibers of immature but 



