FOR WAGGONER’S BIOLOGY 
13 
tion to each and boil. In what way do the contents of the two 
tubes differ? What causes the difference in results? What, then, 
is a test for the presence of glucose? (Some other sugars also re¬ 
duce Fehling’s solution but glucose is the one most commonly 
found in connection with plant and animal life.) 
III. Test for Cane Sugar. Prepare two test tubes with a solu¬ 
tion of cane sugar and water. Add some Fehling’s solution to one. 
Boil. What is the result? Is this a test for cane sugar? Explain. 
Add a drop of dilute hydrochloric acid to the other test tube which 
contains sugar solution. Boil. Then, while its contents are still 
hot, add to the test tube some Fehling’s solution. What is the 
result? What change did the acid cause with regard to the cane, 
sugar? What is a test for cane sugar? 
IV. Test for Oil. Place a drop of oil on paper. Warm the 
paper. What is the result? What then is a test for oil? (Oil may 
also be extracted with ether and obtained in a practically pure 
state. This is another test for oil.) 
V. Test for Protein. Add some of the white of egg (a protein 
substance) to a test tube of water. Boil. What is the result? 
Add some strong nitric acid to a similar preparation of egg albu¬ 
min. Warm this. What is the result? Pour off the acid which is 
in this tube. Rinse with water to remove the nitric acid. Then 
add some ammonia. What is the result? What are two tests for 
protein? 
EXERCISE 14 
NUTRIENTS STORED IN A SEED 
I. The Corn Kernel. 
1. Cut a soaked corn kernel through the center so that the 
embryo is exposed. Place the cut surface in iodine. Locate the 
starchy portion. How are you able to do this? Locate the yellow¬ 
ish portion. This is richer in protein. Is all of the protein in the 
embryo? Why can you not see the protein which is present in 
the endosperm? 
