Physiologie. 293 



carbohydrate during the vegetative period and to the transformation 

 of carbohydrate into oil during the reproductive period. As a spe- 

 cial phase of this relationship between carbohydrate supply and oil 

 formation in soy beans, it was found that when the normal distri- 

 bution of the vegetative and reproductive plant parts was modified 

 by partial defoliation (53 to 60 per cent) the yield of beans was 

 decidedly reduced, but the size of the beans and their oil content 

 were onh^" slightly affected, except in the case of an early-maturing 

 variety. On the other band, the removal of a portion of the blos- 

 soms or young pods caused a notable increase in the size of the 

 beans allowed to develop, but did not materially affect the percen- 

 tage oil content. 



There is always lack of uniformity in the size of the seed from 

 an individual plant; but it was found that there was no correlation 

 between the size of the seed and the percentage content of oil. 



Some varieties of soy beans show a marked tendency to shorten 

 the time required for reaching maturity when planted late in the 

 season, but no correlation was found between the date of planting 

 and the size of the seed or their oil content. These propertiesappear 

 to be influenced more by the character than, by the length of the 

 growing period. 



Different varieties of soy beans grown under the same condi- 

 tions showed marked differences in oil content and very great 

 differences in size of the seed. Although different varieties of cotton 

 showep decided differences in the size of the seed, there was ver}'' 

 little difference in the percentage oii content. The differen varieties 

 of soy beans did not respond alike to changes in seasonal conditions. 



In tests with several varieties of so}'^ beans grown under a very 

 Wide ränge of conditions there were found differences of more than 

 100 per cent in the size of the beans and very large differences in 

 oil content. Here, again, the different varieties were not affected 

 alike by changes in the environment. It was not practicable to 

 grow cotton under such diverse conditions, but the difference in 

 oil content of the seed as grown in the Coastal Piain and the 

 Piedmont regions of the South was greater than the varietal diffe- 

 rences when grown in the same environment. All varieties respond 

 ver)^ much alike to changes in the environment. 



Because of the interdependence of soil and climate with respect 

 to temperature and water supply it is difhcult or impossible to 

 develop far-reaching c-eneralizations as to the specific effects of 

 either independently of the other on plant development. Six Upland 

 varieties of cotton were grown three consecutiveyears on adjoining 

 but contrasted soil t3^pes in northern Georgia. Each year the claj^ 

 soil gave heavier seed than the sandy loam, but the relative oil content 

 on the two soil types varied from year to year. In experiments with 

 several varieties of soy beans only small differences were obtained 

 in the size and oil content of the seed grown on these two soil 

 types. Similar results were obtained with peanuts. Field experi- 

 ments with soy beans and peanuts on sharply contrasted soil types 

 at Arlington Experiment Farm, Va., and vicinity gave more decided 

 differences in size and oil content of the seed. A number of tests 

 with soy beans, peanuts, and sunflower were carried out also on 

 different soil tj^pes under controlled conditions, using for the pur- 

 pose large earthen pots set into the soil. The various tests were 

 carried out under a wide ränge of soil types and climatic condi- 

 tions, and the results as a whole emphasize the fact that the rela- 



