9 DEVELOPMENT OF STARCH. 31 
Development of Starch_—Starch first makes its appearance as 
minute colourless granules in the interior of the chlorophyll 
grains when exposed to sunlight, as previously noticed at page 
_ 29. These primary starch granules rarely grow to any con- 
siderable size, but are dissolved, chemically altered, and poured 
~ outinto the sap, of which they then form a part. A part of 
_ this primary starch may be used by the protoplasm of the cell 
in which it is formed for the manufacture of its cell-wall, but 
by far the greater part is handed down from one cell to another 
Fia. 48. Fig. 49. 
Fig. 48. Tous-les-mois ( x 250). Fig. 49. Potato starch (x 250). 
till it arrives at particular parts of the plant, when it becomes 
reorganised and stored up for future use. In this latter state 
starch assumes its more characteristic appearance. Thus ina 
well-developed Tous-les-mois or Potato granule (figs. 48 and 49), 
we may observe a roundish dark spot, which is termed the 
mucleus or lilum, situated near one end of the granule; and 
Fie; 50. Fie. 51. Fig. 52: 
Fig. 50. Compound starch granules of West-India Arrowroot. After Schlei- 
den.— Fig. 51. Wheat starch (x 250). Fig. 52, Rice starch (x 250). 
surrounding this a variable number of faint lines which alter- 
nate with other darker ones, so that the whole presents the 
appearance of a series of more or less irregular concentric 
Shells placed around a common point. The cause of these 
appearances has given rise to much discussion ; thus at first 
