THE SPERMAPHYTES. 243 



well started, grind to a pulp, mix with water, and let it 

 stand one or two hours, filter, and add some thin boiled 

 starch. Test for starch with iodine at intervals of half 

 an hour. The diminishing intensity of the blue color 

 shows that the starch is diminishing in quantity ; it finally 

 wholly disappears. Test for sugar. Is it found ? What 

 do you conclude as to the presence of a diastatic ferment 

 in the germinating Barley? 



23. Prove that the starch in a plant is a reserve food 

 to feed the plant at times when the formation of new food 

 materials is impossible ; also that a plant can convert 

 sugar into starch. Keep a Geranium or Nasturtium in 

 the dark for a day or two. Test bits of the leaf for 

 starch by dissolving out the chlorophyl with hot alcohol 

 and applying iodine solution. After a time the failure 

 to obtain the blue color proves that no new starch is 

 being formed in the absence of the sunlight, and that the 

 starch previously formed has been used up or transferred 

 to other parts of the plant. Now cut leaves from the 

 plant and place them with the cut ends in a beaker of 

 sugar solution in the dark. Test bits of these leaves 

 daily, after two or three days, for starch until you find 

 that some has been formed. 



24. How do the nutrient fluids get to the portions of 

 the plants that are raised in the air? 



a. Arrange capillary glass tubes, i.e., tubes of very 

 small bore, so that their ends dip into water. Arrange 

 in the same way a lamp wick and a piece of Pine wood. 

 The water can rise a certain height by capillary attraction. 

 It can in no case rise so as to flow over the top of the 

 tube unless the top is in contact with some other object. 

 Will capillarity account for the rise of water in large 

 plants ? 



b. Cut off a Geranium plant a short distance above the 

 soil, and attach to the stump by means of a piece of rubber 



