COTTON BREEDING 309 



From all of the above it follows that it is important to 

 start -nith a pure varietj' that already possesses most of the 

 qualities desired. 



278. Plant-breeders' methods of improving cotton. — 

 In order to make very great or very rapid improvement in a 

 variety or strain of cotton, it is necessary to practice a 

 method requiring much more time and pains than can be 

 spared by any except the few men who make a specialty 

 of plant -breeding. This method is called the " plant-to- 

 row method." It is based on the fact that plants may be 

 excellent bj' reason of either : — 



(1) Favorable surroundings (environment), or by 



(2) Their inherent, or self-contained, excellence. 

 Superiority due merely to favorable environment, such as an 



extra share of fertilizer, abundant space, and other advan- 

 tages, is not hereditary ; but inherent excellence is heredi- 

 tary. It is usually difficult or impossiljle to determine 

 whether the superiority of a selected plant is accidental 

 (due to favorable environment) or inherent. This ques- 

 tion remains unsettled whenever seed from a number of 

 plants are planted together, as in the simplest method of 

 selection before described. 



But bj- keeping the seed of each plant separate, and 

 planting each on a separate row, the next year the parent 

 plant of inherent or inheritable excellence is readily de- 

 termined. For its offspring almost uniformly show the 

 desired quality; while a row grown from a parent plant 

 that was productive merely because of favorable envi- 

 ronment does not show the good qualities of the parent. 

 Hence, selection must be made thereafter only from 

 those rows on which the plants exhibit the proof of ha\'ing 



