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THE HOLE OF NITROGEN IN PLANT-METABOLISM. 



Part iv. — The Nitrogen of Ripening Seeds. 



P.v James M. Petrie, D.Sc, F.I.C., Linnean-Macleay 

 Fellow op the Society in Bio-Chemistry. 



(From (hf Physiological Laboratory of thp University oj 



Sydney.) 



The investigations of Emmerling, Wassilieff, and Schulze 

 have led to the assumption that, during the ripening of 

 seeds, organic nitrogen compounds- are transferred from 

 other parts of the plant, principally the gi-een leaves, to the 

 seeds. As the protein-content of the seeds rapidly increases 

 during the progress of ripening, it is, therefore, assumed 

 that, in the process, the synthesis of proteins has taken 

 place, that the protein is formed where the carbon-assimila- 

 tion is most active, and that it does not accumulate there, 

 but is transferred to the growing parts of the plant. 



It is obvious, since the proteins occurring in the sap of 

 plants possess entirely different properties, both physical and 

 chemical, from the proteins which are stored as reserve-food 

 in the seeds, that a change must take place in the constitution 

 of the former. Now we can conceive of this change only as 

 one of cleavage along the same path as in artificial hydrolyses, 

 and having as end-products the amino-acids. But there are 

 also formed numerous intermediate products, the polypep- 

 tides, diminishing in complexity, from the very slightly 

 altered metaprotein downwards, and including the albumoscs 



