230 HOW CROPS GROW. 
starch-grains are gradually converted from their surfaces 
inwardly into smaller grains of aleurone, 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 dis- 
solves, and even the cellulose stratified upon the interior 
of the cell, fig. 32, wastes away and is converted into 
soluble food (sugar?) for the seedling. 
The Dimensions of Vegetable Cells are very various. 
A creeping marine plant is known—the Caulerpa prolifera, 
Fig. 33. 
fig. 33,— which consists of a single cell, though it is often 
a foot in length, and is branched with what have the ap- 
pearance of leaves and roots. The pulp of the orange con- 
sists of cells which are one-quarter of an inch or more in 
diameter. Every fiber of cotton is a single cell. In most 
