STARCH IN GERMINATING PEAS 



177 



made daily, these being treated with iodine and examined with 

 reference to the progress of starch removal. Other material was 

 fixed in chrom-acetic acid, serially sectioned in paraffin, and 

 stained with gentian violet followed by a rather strong staining 

 with orange-G. 



The cotyledons of the ripe seed are completely packed with 

 starch, the digestion of which, during germination, begins in the 

 peripheral cells on the convex side of each cotyledon. (Fig. 1, a. ) 3 

 A short time later, digestion is to be observed in the peripheral 

 cells of the flat face. The removal of the starch gradually works 

 inward toward the vascular bundles. The enzymotic action at 



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& ■;■■';.? '■:,; ■:■.„ ■ 







... -J ... 





Fig. 1 



any one time seems to be confined to a layer two or three cells in 

 thickness, the starch being almost completely removed from this 

 layer before any marked amount of solution is to be observed in 

 the adjoining cells lying nearer the center of the cotyledon. (Fig. 

 1, b and c). Finally the starch is removed from the entire coty- 

 ledon, except that usually a few groups of cells and a few isolated 

 cells persist in retaining their starch without any apparent change 

 (Fig 1, d). A few exceptional cases were observed, in which this 

 progression of the enzymotic activity was not found, but in most 

 cases it is very definite. 



3 Figures 1, 6, and 7 are made from camera lucida drawings reduced to a magnifi- 

 cation of X*2o. 



