STUDIES OF SEEDS AND SEEDLINGS 11 



The jar must not stand in direct sunlight, the effect of which 

 would be to render the contents wanner than the room. 



It would be well to find by means of another thermometer whether 

 the temperature outside the jar changes in the same direction equally, 

 during the time of observation. 



Is there any connection between the activity of the seedlings, 

 detected by Experiments 1 and 2, and their heat condition indicated 

 by the thermometer in Experiment 3 ? 



EXERCISE IV. INFLUENCE OF TEMPERATURE ON GERMINATION 



Experiment 4. Take 100 seeds of Bean, 100 grains of Indian Corn, 

 and 100 grains of Wheat. Soak all the seeds for twenty-four hours in 

 water. Note the change or changes produced. 



The seeds of each kind are then to be divided into two sets of 50 

 each. Place one set of each kind in a suitable receptacle, where they 

 will be kept moist, but not covered with water (e.g. place between 

 layers of wet blotting paper, or in moist cotton, or in wet sphagnum 

 moss, the receptacle being closed to prevent evaporation). Put the 

 receptacle in a warm place where the temperature will be as nearly 

 75 Fahr. as possible. Treat the other sets in like manner, but expose 

 to a low temperature but, of course, above freezing. Each day 

 record in a table the number of seeds of each kind that have 

 sprouted. What is your inference concerning the influence of tem- 

 perature ? 



EXERCISE V. DIRECTION OF GROWTH OF PLUMULE AND ROOTLET 



Experiment 5. By a chance position of the seed in the soil the nas- 

 cent root, or radicle, on emerging may have its tip directed toward any 

 point but the right one. Ascertain as follows how an inverted seedling 

 behaves. Fit a double roll of blotting paper into a beaker. Moisten. 

 Between the paper and the glass place seedlings, well sprouted, with 

 the roots pointing upward, the plumules downward. They are held 

 in place by the pressure of the paper. But if some of the seeds are 

 large, like the Lupine, tuck wads of cotton in on either side to 

 support the radicle, and prevent it from falling or bending over. 



Pour a little water into the beaker. This, soaking up on the blot- 

 ting paper, will keep the seedlings moist. Cover the beaker to pre- 

 vent drying up. Draw some of the seedlings well enough to record 

 their positions. After two or three days examine and draw again. 



Record the preparation and results of this experiment. Is there 

 indicated anything which might be termed sensitiveness, together 

 with active growth toward or away from the direction of gravity? 



Or are the affected parts simply bent by their own weight? 



