110 CHEMICAL COMPOSITION OF THE PLANT 



potato and apple, mount in water and examine under the microscope. Add 

 a drop of iodine and note the effect. 



8. Starch and Sugar after Germination. Crush a few well ger- 

 minated seeds and put in two test tubes, fill about one-third full of water 

 and shake thoroughly. Boil and test for starch and sugar. 



0. Changing Starch to Sugar. Make a thin paste by boiling starch 

 in two test tubes of water. Allow to cool and add a small amount of 

 diastase or saliva to one. Keep in a warm place for 24 hours and tetft 

 both for sugar. 



10. Oil in Seeds. Crush a seed of castor bean or the kernel of some 

 nut between the fingers and thumb and note the oily character. Rub the 

 seed or nut on a piece of paper for the same purpose. Tie a small amount 

 of crushed seeds or other plant material in a bit} of cheese-cloth and soak 

 in a small dish of benzine; squeeze and remove and allow the benzine to 

 evaporate. Any oil that may be present will be found in the dish. Make 

 a list of vegetable oils of commercial importance and give their sources. 



11. Protein in Flour. Tie a small quantity of wheat flour in a bag 

 and knead under a stream of water. The sticky dough that remains is 

 largely protein. The starch was mostly washed out by the stream of 

 water. 



12. Starch and Protein in Wheat. Cut very thin slices of wheat 

 grain and examine under the microscope. Test for starch. Note that 

 the starch is in the center and in very thin-walled cells. Also note that 

 the proteid (aleurone) is in cells surrounding the starch. Also note the 

 hull is made up of the union of seed and ovary coats. 



QUESTIONS 



1. What compound is found in greatest amount in the plant? How 

 does it get into the plant? Is the total amount entering the plant retained? 

 If not, how does it pass out? 



2. Explain the results obtained in the drying and burning of a 

 piece of wood. How do these elements and compounds become a part of 

 the wood? 



3. What substances found in plants are useful as foods for animals? 

 In what parts of the plant are they found? 



4. Give a list of commercial products of plants. Tell where found 

 and their uses. 



5. Mentjon several plants or products rich in sugar. 



6. From what plants is starch obtained commercially ? 



7. What plants yield oil for commerce? 



8. Mention several stock feeds rich in protein. 



