230 Journal of Agricultural Research voi. m. no. 3 



present investigation the weight of the seed in addition to its percentage 

 composition was determined in order to ascertain the actual quantity of 

 oil which it contained. When practicable, data were collected as to the 

 size and character of growth of the plant as a whole for purposes of 

 correlation and more particularly in dealing with specific factors of the 

 nutrition process as a measure of the relative effects produced by the 

 special conditions of the experiment. The actual yield of seed has not 

 received any special attention, since this is greatly affected by factors of 

 nutrition which have little influence on the problems involved, and, 

 moreover, the matter of crop yields constitutes a separate problem. In 

 analyzing the seed the official method' for the determination of oil was 

 followed, using anhydrous ether as the solvent. 



OIL CONTENT OF SEED AT SUCCESSIVE STAGES OF DEVELOPMENT 



It has been shown that the accumulation of oil in the seed does not 

 set in actively during the very earliest stages in the development of the 

 seed, and the work of Ivanow (1912) suggests that there is a period of 

 very intense oil formation, which occurs about midway between bloom- 

 ing and the final maturity of the seed. This raises the question as to the 

 existence of a "critical period" in oil formation which would have an 

 important bearing on the effects of external conditions on the quantity 

 of oil produced. Samples of soy beans and of cotton seed were collected 

 at different stages of maturity, to secure more definite information on 

 this point. The weight of the seed also was obtained in each case, so 

 as to ascertain the changes in the absolute as well as the relative oil con- 

 tent. To arrest respiration promptly and thereby avoid changes in com- 

 position, the immature seeds were dried in the oven at 70° to 80° C. In 

 the case of the soy bean 5 to 6 pods were picked from each of 100 to 125 

 plants in taking the samples. The material was grown at the Arlington 

 Experiment Farm, Va., the Peking soy bean in 1910 and the others in 

 191 2. The several pickings from each variety were taken from the same 

 plants at stated intervals, but for obvious reasons the different pickings 

 do not necessarily represent the actual growth made by the beans in the 

 intervals covered. They are strictly comparable, however, as to the 

 relation between the oil content and the size of the seed at the several 

 stages of maturity. In the case of the cotton seed care was taken to 

 obtain the same number of immature and mature bolls from each plant, 

 and these were always taken from the same branch, about 12 plants 

 being used for each pair of samples. The results obtained are shown in 

 Tables I and II. 



' Wiley, H. W.. et al. Official and provisional methods of analysis. Association of Official Agricultural 

 Chemists. U. S. Dept. Agr., Bur. Chem. Bui. 107 (rev.), 272 p., 11 fig. 1908. 



