12 Introduction to Botany. 



a compound microscope, using a | or J inch objective. 

 Starch grains will be seen of various shades of purple, 

 depending on the degree of action of the iodine ; while 

 other granules, whose substance, called proteid, is closely 

 related chemically to the white of an egg, will appear 

 from yellow to brown. These are the two chief classes of 

 reserve food in the seed of Lima bean. The fact that starch 

 is present in large quantities is manifest by the deep 

 purple color which appears when a piece of cotyledon is 

 placed in a drop of iodine. A compound microscope 

 would therefore not be necessary to demonstrate the mere 

 presence of starch. 



32. Mount in a drop of iodine, as before, scrapings 

 from the cut surface of soaked Indian corn, and note the 

 presence of both starch and proteid. 



33. Treat in a similar manner some scrapings from the 

 reserve food materials of castor bean. The regular brown 

 bodies are proteid, while the irregular yellow or brown 

 bodies and circular masses of varying sizes are castor oil. 



34. Boil in Fehling's solution (see page 385) in a test 

 tube a dry crushed seed of Lima bean, and note whether 

 the presence of glucose is demonstrated by the production 

 of a red precipitate of cuprous oxide. Treat in a similar 

 manner a seedling which is somewhat advanced in germi- 

 nation, and seeds and seedlings of castor bean and Indian 

 corn. State in your notes your deductions as to the 

 changes which the reserve materials in seeds undergo in 

 the process of germination. 



35. Place moist white pine sawdust to the depth of 

 about an inch in four wide-mouth bottles. 1 



Put several grains of Indian corn that have lain in water 

 over night into two of these. Cover the corn with about 



1 Such as No. 2750 in the catalogue of Whitall, Tatum, & Co., Philadelphia. 



