414 



STORAGE SYSTEM 



in thickened cell-walls in the form of mixtures, or combined to form 

 compounds of a higher order of complexity. 



The mobilisation of reserve-cellulose during germination is an 

 enzymatic process, which presents many points of resemblance to the 

 hydrolysis of starch-grains. In Impatiens Balsamina, according to 

 Heinricher, the thickening layers disappear gradually, but are often 

 removed much more rapidly from certain parts of the wall than from 



Fig. 162. 



Cotyledonary storage-tissue of Impatiens Balsamina. A. Resting seed. B. Germina- 

 ting seed. In B the secondary thickening layers of the walls, which consist of 

 amyloid, have undergone partial solution. After Reiss (from Frank's Text-book). 



others (Fig. 162 b). The middle lamellae remain intact, and finally 

 form the thin partition-walls of the photosynthetic parenchyma into 

 which the storage-tissue of the cotyledons becomes transformed, after 

 it has been depleted of its reserve materials. In other cases 

 (Tetragonolobus, Lupinus, Gooelia latifolia, etc.), according to Nadel- 

 mann, the layers which are about to be dissolved, first of all acquire a 

 radial striation. Then wedge-shaped fissures appear, which become 

 enlarged by corrosion ; sooner or later the thickening layers dissolve, 

 usually in a very irregular manner. Here also the middle lamella 

 generally persists. 



Among the carbohydrates which are stored in a state of solution in 

 the cell-sap, the various sugars are by far the most important. Cane- 

 siigar, for example, accumulates in the storage-tissue of the Beet-root 

 at the end of the first vegetative season, while the fleshy bulb-scales of 

 the Onion contain a mixture of glucose (grape-sugar) and other sugars. 

 Almost all storage -organs, in fact, contain a certain amount of sugar. 



