260 NATURE STUDY AND AGRICULTURE 



starch is that the boiling water causes the walls of the starch 

 granules to burst open and the iodine can act more readily 

 upon the starch. Pour a little boiling water over some 

 flour and test it for starch; over cornmeal, oatmeal; corn- 

 starch, etc. 



Soak some grains of corn for forty-eight hours, or half 

 an hour in hot water. Each pupil should have at least two 

 grains. At the pointed end of the grain find the tip cap. 

 Remove this. The cap may be lacking on some grains, 

 having been left on the cob. With a knife or a pin remove 

 the hull. You will see that the grain is covered with a thin, 

 smooth material that with care may be scraped off with 

 a knife. This is called horny gluten. Now dig out the 

 germ or embryo. (See lesson on germination of seeds.) 

 Split open the remaining part of the grain. How many 

 kinds of material are left? Place the white, granular 

 material found near the top of the grain in a pile. Add to 

 it the same kind of material found near the tip. Put the 

 hard, solid-looking substance in another pile. You now 

 have six different substances found in your grain of corn. 

 Test each of these with iodine just as you did your potato 

 starch and flour. It is better to crush them as much as 

 possible before putting on the hot water. What part 

 shows the most starch ? It is probable that the soft granu- 

 lar part will turn the darkest blue. This part is known as 

 crown starch. The solid, hard part, if thoroughly boiled, 

 will show some starch. This is called horny starch. 

 What parts do not contain any starch? This means of 

 course that there must be some substances other than starch 

 in the grain of corn. 



Remove some fresh embryos from soaked grains and 



