The Occurrence of Organic Phosphorus 

 Compounds in Plants* 



INTRODUCTION 



It has been recognized for a long time that only a small part of 

 the total phosphorus contained in plant material is present as inor- 

 ganic phosphate because only very small quantities of phosphoric acid 

 could be precipitated from solutions obtained by digesting powdered 

 plant material, rich in phosphorus, in water or dilute acids (Hart and 

 Andrews 1903). In order to determine total phosphorus it was neces- 

 sary either to ash the material or subject it to complete hydrolysis with 

 mineral acids. 



It is evident, therefore, that the greater percentage of the phos- 

 phorus existing in plant cells is combined in some way with organic 

 compounds. The knowledge of the various groups of organic phos- 

 phorus compounds existing in plants has been gradually developed 

 through the efforts of numerous investigators. Although much work 

 has already been done on this subject, the field is not exhausted ; future 

 investigations will probably reveal a number of new phosphorus com- 

 pounds elaborated in plant cells. 



About the middle of the last century it was found that a small 

 percentage of the phosphorus in vegetable material, particularly in 

 seeds, could be extracted with ether or other solvents for fats (Knop 

 1860 and Topler 1861). This class of ether-soluble phosphorus com- 

 pounds was shown to be closely related to lecithin and the phospha- 

 tides, if not identical with similar substances isolated from animal 

 tissues (Hoppe-Seyler 1867; Jacobson 1889; Schulze and Likiernik 

 1891). The wide distribution of lecithin in the plant world was shown 

 by Heckel and Schlagdenhauffen (1886). The plant phosphatides have 

 been extensively investigated in Schulze's laboratory. A large num- 

 ber of important papers dealing with methods of estimation, com- 

 position and properties have been published by Schulze and Winter- 

 stein and their students. 



* The experimental work reported in this thesis was done in the Chemical 

 Laboratory of the New York Agricultural Experiment Station, Geneva, N. Y., 

 in the Chemical Laboratory of the University of Berlin and in the Ludwig Mond 

 Biochemical Research Laboratory of the Institute of Physiology, University 

 College, Lo'ndon; and the series of papers dealing with this subject, as given in 

 the bibliography, was originally published in the "Journal of Biological Chemistry." 



