522 BOTANY OF CROP PLANTS 



characters so badly mixed up as to make it impossible to refer them to any 

 particular group. It is well known that our American cottons hybridize quite 

 readily under field conditions. . Examples: Breeden, Boyd, Roby, Tucker. 



Environmental Relations. — Cotton is a tropical plant. 

 The upper latitudinal limit of cotton growing in this country 

 is about coextensive with the summer (June, July and Au- 

 gust) isotherm 77°F. The plant is extremely sensitive to low 

 temperatures, and even a light frost in the fall stops its 

 development. It seldom matures in less than i8o days. 

 The plant not only requires a high temperature, but also 

 one not subject to fluctuations, as such conditions cause 

 premature ripening. After the plant has attained its vege- 

 tative growth, the ripening of fruits and seeds is favored by 

 cooler nights than prevailed up to that period. 



Light, frequent showers which permit of an abundance of 

 sunshine favor the development of the plant. Too much 

 rain is liable to stimulate an excessive development of vege- 

 tative growth at the expense of fruit formation. 



Upland cottons are adapted to a variety of soils, while the 

 Sea Island varieties are best suited to soils with low water- 

 retaining capacity, and of medium fertility. 



Picking and Ginning of Cotton.— Cotton is picked by 

 hand, and loaded into wagons. This labor is performed 

 almost exclusively by negroes. The seed cotton is removed 

 from the wagon by means of a suction fan, and carried over 

 a single gin or battery of gins. It passes into chutes over the 

 feeders, and is then fed evenly to the gin saws, where the lint 

 and seed are separated. The^seeds are carried by a screw 

 conveyor to the seed house or seed bin. The lint cotton is led 

 from the gin saws through a flue to the condenser. Here it is 

 cleaned, smoothed out into sheets or bats, wrapped and tied 

 into bales. The usual size of a cotton bale is 27 by 54 inches 

 and'the weight about 500 pounds. Sea Island cotton is ginned 



