48 



THE VEGETABLE CELL IN GENERAL. 



23 



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starch, or with great regular- 

 ity, as in wheat. This point is 

 known as the nucleus, or hilum. 

 If two or more nuclei are dis- 

 cernible, the granule is said to 

 be compound. 



Occasionally many small sin- 

 gle granules cohere slightly to 



form an aggregate which can be easily broken. According to 

 Wiesner, there may be as many 

 as 30,000 granules in a single 

 aggregate of this kind. 



Both simple and compound 

 granules may occur in the same 

 cell, but some plants have only 

 simple, and others only com- 

 pound granules. Canna and 

 Curcuma may be cited as exam- 

 ples of the former ; Jatropha, of 

 the latter. 



Since starch occurs in every 

 plant in all stages of development, the size of the granules must 



be extremely variable. Nevertheless, a 

 statement of the more common limits may 

 aid in their identification. 



Wiesner gives the following limits of size 

 for some of the more common sorts of starch, 

 first grouping them into small, medium, and 

 large granules. 



Small granules (from 0.002 to 0.015 mm.) : 

 as the simple granules of rice, oats, buck- 

 wheat ; also the smaller granules of wheat, rye, barley, etc. 



Medium granules (from 0.02 to 0.05 mm.) : as the compound 

 granules of rice and oats, the larger ones of wheat, rye, and 

 barley, the simple granules of Indian corn, and of the common 

 leguminous plants. 



Large granules (distinguishable as grannies to the naked eye) : 

 as the simple granules of Curcuma leucorrhiza, Canna edulis, 

 potato, etc. 



FIG. 23. Starch-granules from the bulb of Phajus grandifolius, showing the nu- 

 cleus at the upper part and the starch generator or amylogenie body below. 8 f . 

 (Schimper.) 



FIG. 24. Cells from potato-tuber, showing starch-granules (Schmidt.) 

 FIG. 25. Starch-granules from sarsaparilla. (Berg and Schmidt.) 



