10 STUDIES OF SEEDS AND SEEDLINGS 



The cork, pierced by two glass tubes that penetrate a quarter of an 

 inch or so beyond the inner surface, should be put in with care to 

 exclude even the smallest bubbles of air; and the water should rise to 

 fill the tubes completely as the cork is pushed in. Place the fingers 

 tightly over the glass tubes and invert the bottle. Stand it mouth 

 down in a dish of water (e.g. a tumbler). Be sure no air is present in 

 the bottle. 



Displace the water in the bottle by hydrogen gas. Lead the hydro- 

 gen from the flask into the bottle only after all air has been driven 

 off in the flask. Allow the apparatus to stand as now adjusted in 

 some situation favorable to the growth of the beans. 



Beside it place a quite similar arrangement, also with sprouted 

 beans, but let this one contain air in place of hydrogen. 



Make full notes of the preparation and conditions of this experi- 

 ment. Several days may be required for the result to be plainly 

 seen. Thereafter finish the notes on the experiment. 



In this exercise hydrogen, a harmless gas, is used to give an 

 atmosphere devoid of oxygen. The second jar, filled with air, has of 

 course a supply of the latter gas. What is your inference concerning 

 the presence of oxygen? 



Experiment 2. In a fruit jar one-third full of sprouting corn place 

 a small beaker of limewater. Cover the jar tightly. Another beaker 

 with like contents is to be placed in an empty jar beside the first, and 

 this jar likewise closely covered. After an interval of from one to 

 several hours observe the appearance of the liquid in both beakers. 

 Note any difference. 



Take a small beaker of fresh limewater. Breathe gently upon it 

 till a change is produced. This action of one's breath upon limewater 

 has what bearing in explaining the effect observed in the jar of sprout- 

 ing corn? What is the object of the second jar and beaker? 



Experiments 1 and 2 will enable the student to infer 



(1) Whether the atmosphere supplies anything more than moisture 

 to the germinating plant ; (2) Whether the plant gives back anything 

 into the atmosphere. 



What action necessary to the life of animals does this double pro- 

 cess in growing plants resemble ? 



Experiment 3. Having removed the beaker from the jar of seed- 

 lings used in the previous experiment, tie a cloth over the mouth of 

 the jar. Near by lay a thermometer. When the mercury column has 

 become stationary, note the reading accurately (without handling the 

 bulb), and passing the instrument through a small hole in the cloth, 

 insert its bulb amongst the seedlings. 



Within five or ten minutes observe with exactness the temperature 

 of the seedlings. Is it higher or lower than that of the room? 



