14 BOTANY. 



(6) Soak a few moss-leaves in alcohol for twenty-four hours, and 

 note the decoloration of the chloroplasts. Note the green color given 

 to the alcohol. 



(c) Carefully study the cells of several fungi, as Lilac Mildew 

 (parasites), toadstools, pufEballs, etc. (saprophytes), and note the ab- 

 sence of chlorophyll. 



(d) Examine the yellow cells of the petals of the Nasturtium (Tro- 

 paeolum), and of the root of the carrot for chromoplasts. Examine 

 also the red cells of a ripe tomato. 



(«) Make sections of a potato-stem grown in darkness. Compare 

 this with a stem of the same plant grown in light. 



(f) Make sections of blanched celery. Compare with unblanched. 



(g) Dissolve out the chlorophyll (by alcohol) from a specimen (any 

 of the foregoing) and then treat with iodine. Note the brown color 

 given to the bleached chloroplasts, showing them to be protoplasm. 



20. Starch.. — Many cells of common plants contain little 

 grains of starch (Fig. 9). In some cases, as in the potato- 

 tuber, the cells are only partially filled, but in other cases, 

 as in rice, wheat, Indian corn, etc., the stprch is packed so 

 closely in the cells as to leave very little unfilled space. 



21. The starch of every plant is originally manufactured 

 in chloroplasts, that is, in masses of stained protoplasm. 

 It moreover forms only in the light, so that plants which 

 have no chlorophyll, or which grow in darkness, do not 

 make starch. After starch has once been formed it may 

 be transformed to sugar or some other soluble substance, 

 and diffused to distant parts of the plant, where by the 

 activity of the leucoplasts it may be deposited again, this 

 time independently of the presence or absence of light 

 (Fig. 10). 



22. Chemically, starch is much like sugar and cellulose, 

 and like them it is composed of carbon, hydrogen, and 

 oxygen (C,II,„Oj). It contains water in its organization, 

 which may be driven off by heat, or by the application of 

 reagents, when it loses its structure. 



