100 NATURE TEACHING 



tubes in a glass of warm, not boiling, water. After half 

 an hour test one for starch and the other for sugar. It 

 should be found that the starch has disappeared, and that 

 sugar has been formed. 



To two other portions of starch in water add a little 

 malt (obtained from a brewery). Keep warm in the 

 same way, and afterwards test for starch and sugar. It 

 should again be found that the starch has disappeared 

 and that sugar has been formed. 



Repeat the above experiment, but instead of using 

 malt from a brewery, take a good number (50 to 100) of 

 just-sprouted barley grains. Break off the young shoots, 

 and grind them up with a very little water. Add some 

 of this paste to the two tubes containing starch, and keep 

 just warm for an hour or two. Test the tubes now for 

 starch and sugar. As in the previous experiments, it 

 will probably be found that the starch has gone, and 

 sugar has been formed in its place. Germinating barley, 

 therefore, contains something which can change starch 

 into sugar. 



Gather during the night twenty or thirty leaves of 

 the garden pea, or garden nasturtium. Rub them to a 

 paste with a little water, and add this liquid to two more 

 samples of starch in water. Keep warm, and test after 

 a few hours for starch and sugar. The same process 

 will be found to have gone on, showing that these green 

 leaves, like the germinating barley, contain a substance 

 able to change starch into sugar. 



