CHAP, vi The Metabolic Processes 383 



the protoplasm. Grains growing in connexion with chloro- 

 plastids sometimes become separated from the latter and 

 are then added to by the general protoplasm wherever the 

 two are in contact. Schimper's leucoplast, according to 

 him, is a formative material which becomes transformed 

 into the substance of the grain. 



A paper published by Konigsberger in 1893 calls for pass- 

 ing notice, as its author, while admitting the existence of 

 the leucoplasts in certain cases, disputed their universality. 

 He quoted cases of formation by their agency, but claimed 

 to have seen many instances of their appearance without 

 such intervention. In Maranta amndinacea he claimed to 

 have observed cases in which the starch grains originated 

 in contact with a leucoplast, but subsequently became free 

 from it and afterwards grew while embedded in the proto- 

 plasm. He controverted Eberdt's statement as to the 

 nature of the leucoplast. 



It will be seen that these researches left a little uncer- 

 tainty as to Schimper's results, chiefly as to the existence 

 of leucoplasts in the regions in which the process of photo- 

 synthesis is impossible. The question was, however, finally 

 set at rest by the appearance of the contribution made 

 by A. Meyer in 1895, in the shape of his very complete 

 treatise Untersuchungen uber die Starkekorner , in which 

 the whole subject was reviewed and a very large number 

 of new investigations detailed. During the intermediate 

 period several researches supporting Schimper's position 

 appeared, chief among them being the works of Dodel and 

 of Binz, both of which were published in 1892. 



In one respect the relation of the plastid to the starch 

 grain was not quite accurately stated by Schimper. By 

 the application of delicate methods of staining Meyer found 

 that the grain never ruptures the plastid, though it may 

 stretch it very considerably. Even in the case of the most 

 excentric grains a thin layer of the substance of the plastid 



