The Bulletin. 9 



If we take a particular variety of any plant, as cotton, and grow it in 

 "widely different soil environments (climate remaining the same) certain 

 adaptive changes will appear, enabling the plant to correspond more 

 •completely with the various new conditions. Now, if by careful and 

 persistent selections the grower each year weeds out all plants but those 

 most nearly corresponding to the new environment, he will soon find 

 these adaptive variations to have become so intensified and his plants 

 to have undergone such a pronounced physiological change that he can 

 legitimately say a new variety of cotton has appeared in his field. If, 

 for example, we take a variety of cotton having a small stem, leaf and 

 boll, grown for generations on the Norfolk sand, and transplant it to the 

 Yazoo loam, we will have changed the environment of the plant by 

 -changing the soil type. We will have increased the food and moisture 

 supply of the plant enormously. In order to utilize the increased supply 

 ■of feed and drink the plant begins to gradually enlarge its stem, leaf and 

 boll. JSTot all the plants in the field may show a pronounced adaptive 

 change at once, but here and there will be found a plant with an 

 iibnormal development. The enlarged boll may appeal to the grower as 

 ■a desirable characteristic, and he may, therefore, select for seed only 

 those plants that have the extra large boll. The following year he will 

 plant these selected seed in the same soil environment and again select 

 seed only from the plants having the enlarged stem, leaf and boll. This 

 practise of selection and adaptation is continued till every plant in the 

 field closely corresponds to the ideal set by the grower, and, perhaps 

 ■without intending to do so he has produced a new variety of cotton, 

 thoroughly adapted to the new soil environment. 



After this, big boll variety of cotton has been grown for a number of 

 years on this rich bottom land soil, we w^ll suppose the grower takes the 

 seed and plants them on the upland soil again. He will have again 

 changed the environment by changing the soil type. The available food 

 and moisture supply will have been greatly decreased, but the desire of 

 the plant for a large supply of these will not have been diminished. It 

 is thus subjected to a process of starvation, which causes it gradually to 

 decrease the size of stem, leaf, and boll in order to continue its existence 

 under the changed conditions of life. Early maturity or some other 

 •characteristic of upland plants growing under restricted food supply may 

 «uit the grower's fancy in some of the plants, and these he will select for 

 planting the following year. Should he continue this practise of select- 

 ing and adapting the plants to a particular type of upland soil for a 

 number of years, he will finally have developed a variety of cotton 

 having a small stem, leaf, and boll peculiarly adapted to the upland 

 «oil, as he did in the case of the bottom land soil. It is thus possible to 

 take a variety of plant and, by changing the soil environment, induce a 

 radical change in its characteristics, even to the extent of creating a 

 new variety. 



Some twenty years ago Director Tracy, of the Mississippi Experiment 

 Station, found that "many varieties of cotton which will produce a 

 strong, long, silky fiber when planted on rich river bottom soil soon lose 

 their superior qualities when grown on the dryer hill lands," and that 

 "the percentage of lint also varies with the soil on which it is grown." 



