* 



ELEMENTS OF ORGANIZED STRUCTURE. 251 



from their surfaces inwardly into smaller grains of aleu- 

 rone, which, finally, when the seed is mature, completely 

 occupy the cells. 



In the sprouting of the seed similar changes occur, but 

 in reversed order. The nucleus reappears, the aleurone 

 dissolves, and even the cellulose * stratified upon the inte- 

 rior of the cell (Fig. 32) wastes away and is converted into 

 soluble food (sugar ?) for the seedling plant. 



Fig. 33. 



The Dimensions of Vegetable Cells are very vari- 

 ous. A creeping marine plant is known the Caulerpa 

 prolifera (Fig. 33) which consists of a single cell, though 

 it is often a foot in length, and is branched with what 

 have the appearance of leaves and roots. The pulp of 



* Or more probably metarabin, paragalaetin, xylin, or the like insol- 

 uble substances, which as yet have been but imperfectly distinguished 

 from cellulose in the thickened cell-walls. 



