A^VrjUITIOA''. 



169 



236. Storage. — In the higlu-r plants storage places are 

 secured by the enlargement of roots, sterns or lca\'es, to form 



O /5 



Fig. 174. — Reserve starcli. .-I, two cells of a potato, showing enclosed starch grains 

 The other contents not shown. /^, compound starch grains from a grain of oats 

 Three of the component granules of a large grain are shown separately. C, starch 

 grains from a beau. All highly magnified. — After Kerner. 



reservoirs. Similar specialization of parts of lower ])lants 

 occurs. Carbohydrates are somclinics transformed into fats 

 for storage purposes, Imt carbo- 

 hydrate and jjroteid reserve food 

 is usually solid. Reserve car- 

 bohydrates usually occur in the 

 form of starch, sugar, cellulose, 

 gum, etc. Reser\e proteids are 

 usually in the form of aleurone 

 grains. The starch is deposited in y - f, 

 the form of large rounded or oval 

 grains (sphere-crystals), which often 



y 



', c 



00 







Fic;. 175. — Aleurone (proteid) grains, 

 show layers Ot differcTlt COnipOSltlOll /, from seed of peony. a\ frorr 



tlie outer, />, from the middle, c, 

 and density (fi^^- I74)- Fats occur from the inner layers. //, from 



in liquid form as droplets of vari- 

 ous size, and are only rarely solid. 

 Aleurone grains are really vacuoles 

 filled with reserve proteids. Some of the proteids often 



seed of castor bean, a, in alcoho 

 /', after treatment with iodine solu- 

 tion and alcohol. Tn both. ,<', glo- 

 boid ; ^-, crystalloid. Very highly 

 magnified.— After Zimmermann. 



