SEEDS. 7 



1. Compare the grains of corn starch with those of the 



bean and wheat. Draw. 



2. Test with iodine solution. 



IV. Cut a grain of oats in two, obtain some of the 

 starch as directed in the preceding cases, and examine 

 microscopically. The compound grains of starch present 

 a widely different appearance from the simple ones of 

 Indian corn, wheat, and beans. Study their structure 

 carefully, and draw one or more. Test with iodine. 



From this and preceding observations what do you con- 

 clude in regard to the usual form and structure of starch ? 

 What as to its reaction with iodine ? 



V. Cut a sunflower akene in two, and remove a small 

 portion of the endosperm. Mount in water and apply 

 slight pressure to the cover glass. Under the compound 

 microscope numerous highly refractive drops of oil will be 

 seen coming out of the broken tissue. Focus carefully on 

 an oil drop, and observe its sharply denned border. What 

 changes does it undergo as the focus is altered? 



Various other oily seeds, such as those of the squash, 

 tomato, pine, English walnut, etc., may be studied in the 

 same way. Enough of these should be examined to ensure 

 familiarity on the part of the student with the appearance 

 of fatty oil under the microscope. 



VI. Soak a date seed in water a day or more until it 

 can be cut easily. Pare off a portion of it with a knife or 

 scalpel, so as to expose a smooth, even surface, and then 

 with a razor make extremely delicate sections of the endo- 

 sperm. Mount some of these in glycerine, and others in 

 Schulze's solution. Microscopic examination shows that 

 the date seed consists chiefly of the greatly thickened 

 walls of the cells that compose its substance. Watch the 



