BLEHENTS OF OBGANIZED STBUCTtlEE. 351 



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. 33) wastes away and is converted into 

 soluble food (sugar ?) for the seedling plant. 



Fig. 83. 



The Dimensions of Vegetable Cells are very vari- 

 ous. A ci'eeping 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 metarabln, pa'ragalactln, xylin, or the like insol- 

 uble substances, whtcli as yet have been but imperfectly distinguished 

 from cellulose in the thickened cell-walls. 



