450 



MANUAL OP BOTANY 



we have many oases in which the deposition of starch is effected 

 by the protoplasm of the cell. Such grains are generally very 

 small, and show no structure. Instances of their occurrence have 

 been already given. They are generally seen in the interior of 

 the plant in reservoirs which are only temporary. 



Carbohydrate materials are deposited in other forms in 

 many plants. The root of the beet (Beta vulgaris) contains 

 large quantities of cane sugar, as do the stems of the sugar- 

 cane. The bulb-leaves of the onion abound in grape sugar. 

 Many fruits contain different kinds of sugar. Inulin is stored 

 in the tubers and tuberous or fleshy roots of many of the Com- 

 positce. Glycogen occurs in the hyphse of many of the Fungi. 



Fig. 1187. 



Fig. 1188. 



Fig. 1187. Gi'oup of rod-like leuco- 

 plastids, 2, each bearing a starch- 

 grain, s, collected round the nu- 

 cleus, 71, of a cell of the pseudo- 

 bulb of an Orchid (P/iaJus grandi- 

 folius). X 500. (After Schimper.) 



Fig. 1188. Potato - starch 



( X 260). Fig. 1189. A. Com- 

 pound ; B. Semi-coinpouud gra- 

 nule of starch. 



In many Palms the carbohydrate is stored in the shape of cellu- 

 lose, the walls of the endosperm of the seeds being enormously 

 thickened. The cellulose is here formed by the protoplasm 

 of the cells, in the same way as is that which constitutes the 

 thickening layers of the cell-waUs of the vegetative part of the 

 plant. 



The mechanism of the storage of sugar is not accurately 

 known, but we may argue from analogy that it is brought about 

 by the living substance of the cells, by which also, though 

 diffusible, it is no doubt retained within them. 



Proteids are stored similarly; in the meshes of the proto- 

 plasm of all cells there is a certain accumulation in amorphous 



