12 



BOTANY. 



may become active again upon the access of water and the 

 proper temperature. Possibly some of it serves as food 

 for protoplasm in the germination of seeds. 



Practical Studies. — (a) Mount in alcohol a thm slice of a ripe pea. 

 Note the small granules (along with large starch-grains) in the cells 

 (Fig. 5). Apply iodine, which will stain the aleurone yellow or 

 brownish-yellow. 



(J) Make a similar study of the aleurone of the bean. 



(c) Make sections of the foregoing and mount in water to observe 

 the solution of the aleurone grains. The process may be hastened 

 by adding a very little potassic hydrate. 



(d) Make thin cross-sections of a wheat-kernel and study the gluten 

 (aleurone) cells of the inner bran. Add iodine. 



(«) Make a similar study of the bran of rye, oats, and Indian corn. 



26, Crystals. — Some cells of certain plants contain crys- 

 tals (Fig. 7). These are of 

 various shapes, one of the 

 most common forms being 

 needle-shaped, while others 

 are cubical, prismatic, etc. 

 They are frequently clus- 

 tered into little masses. 



27. Crystals are for the 

 most part composed of cal- 

 cium oxalate. That is, they 

 are a combination of lime 

 and oxalic acid. A few have 

 a different chemical compo- 

 sition — as the calcium carbonate crystals found in nettles, 

 hops, hemp, etc., besides others of still more infrequent 

 occurrence. 



28. Crystals appear to be the residues from chemical re- 

 actions which take place in the interior of plants, and they 

 probably have no further use. 



Fio. 7.— Crystals of calcium oxalate. 

 The right-hand portion of the fiprure 

 shows two cells of the Rhuharh, with 

 their contained crystals, and one en- 

 larged. On the left is a crystal from 

 the beet. Much magnified. 



