VII 



THE HISTOLOGY OF THE CELL 



which is eventually converted into starch. The starch grains 

 are formed inside the chloroplasts. 



Chloroplasts ultimately undergo decay, when, as in the case 

 of frilling leaves, all that is left of them are a few yellow granules. 

 During autumn the nutritive matters in the cells of the leaves 

 are carried to other parts of the plant to be stored up for future 



FIG. 106. Epidermis from under side of a leaf of Iris, showing chloroplasts. 

 A, surface view ; B, in transverse section ; s, stoma ; a, air cavity ; f, depression ; 

 c, cuticle. (X 240.) (S.) 



use ; and with these nutritive materials the greater part of the 

 chloroplasts are removed. In the Copper Beech the chlorophyll 

 is masked by colouring matter, which is dissolved in the 

 cell-sap. 



Leucoplasts. In those cells not exposed to light, colourless 

 granules are found ; these are called leucoplasts. Leucoplasts 

 may IDC converted into chloroplasts if the cell in which they are 

 present is exposed to light. The change of colour which a 

 Potato may undergo when exposed to light is owing to some of 



G 2 



