COMPARATIVE UTILIZATION OF THE MINERAL CON- 

 STITUENTS IN THE COTYLEDONS OF BEAN SEEDLINGS 

 GROWN IN SOIL AND IN DISTILLED WATER 



By G. Davis Buckner l 

 Chemist, Kentucky Agricultural Experiment Station 



The experiments of Schroder on the distribution of organic and mineral 

 constituents in seedlings of the kidney bean, Phaseolus vulgaris, pub- 

 lished in 1868 2 show that, in his fourth stage of germinating, when the 

 second and third joints with the trifoliate leaves have formed, the coty- 

 ledons, which have become much reduced in size and more or less shriv- 

 eled, still retain a considerable proportion of their mineral matter unused. 

 Schroder's analyses show that these shriveled cotyledons retain about 

 nine-tenths of their original calcium, whereas not more than one-fourth 

 of their phosphorus and about two-fifths of their potassium, sodium, 

 and magnesium remain. In regard to the calcium, however, Scroder 

 points out that his determinations appear to be too high and that this 

 result should be verified. In describing Schroder's experiments Pfeffer 3 

 remarks that — 



complete removal of all of the essential elements is never possible, for even in a 

 starved plant, certain essential structural constituents can not be mobilized or 

 consumed. 



In 1915, the author of this paper published some results 4 showing that 

 when the Kentucky Wonder garden bean was grown in distilled water, 

 approximately 86 per cent of the calcium, 50 per cent of the phosphorus, 

 and 40 per cent of the magnesium remained unused in the cotyledons as 

 compared with the amounts found in the normal cotyledons. In this 

 experiment the seedlings had been permitted to grow in distilled water 

 until they became etiolated and died from lack of food. These figures 

 approximate those given by Schroder. 



The following experiment was undertaken with the view of comparing 

 the degree of utilization of the total ash and the elements calcium, mag- 

 nesium, and phosphorus in the cotyledons of bean seedlings grown in 

 distilled water and in garden soil. 



In starting the experiment it seemed of primary importance to deter- 

 mine the distribution of the total ash and the elements calcium, magne- 

 sium, and phosphorus, which were to be studied, in the separate portions 



1 The author gratefully acknowledges Dr. A. M. Peter's careful criticism of this manuscript. 



2 Schroder, Julius, untersuchung Cber die vertheilung des stickstoffs und der mineral- 

 best andtheilE bei keimung der schmtnkbohne. In Landw. Vers. Stat., Bd. 10, p. 493-510. 1868. 



3 Pfeffer, W. the physiology of plants . . . ed. 2, transl. and ed. by Alfred J. Ewart. v. 

 1, p. 584. Oxford, 1900. 



4 Buckner, G. Davis, translocation of mineral constituents of seeds and tubers of certain 

 plants during growth. In Jour. Agr. Research, v. 5, no. n, p. 449-458. 1915. 



Journal of Agricultural Research, Vol. XX, No. n 



Washington, D. C Mar. 1, 1921 



xd Key No. Ky.-io 



(875) 



