142 Education through Nature 



ide, because they waste; but, in sunlight, the oxygen 

 given off because of the breaking up of carbon dioxide 

 and water to form starch, is much in excess of the carbon 

 dioxide. Exhalation of oxygen in plants is due to 

 photosynthesis, the formation of starch from H 2 O 

 and CO 2 . 



XIII. On Germination, (a) Make a moist-chamber 

 from a common plate and a bell jar (a saucer with a 

 tumbler inverted over it will do). Place in the bottom 

 of the chamber a circular piece of filter-paper not so 

 large as the cover. Moisten well, and place upon the 

 moistened paper the seeds that are to be studied. 

 Place a second moist paper over the seeds till they 

 are well sprouted. Keep the papers moist, (b) In a 

 tin basin filled with black soil or sawdust, place the 

 seeds to be sprouted. Moisten the contents and keep 

 moist, (c) If convenient let each member of the class 

 stir up a little patch of ground in the school-yard and 

 plant seeds of various kinds, such as peas, beans, flax, 

 wheat, corn, and flowers. 



XIV. On Tropisms, Direction of Growth, (a) In a 

 tin basin or wooden box filled with black soil or sand, 

 plant some beans. Keep moist. As the plants come 

 up, notice the curvature of the stem, and how it gradu- 

 ally straightens out. Leave the dish in the same posi- 

 tion for a week or two. Observe how the plants bend 

 towards the window, the source of light (heliotropism). 

 (6) Take a coarse sponge; soak it and squeeze it 

 dry; fasten a pin, bent into a hook, to a strong cord; 

 hook the pin securely into the sponge; fill the pores 

 of the sponge with kernels of wheat; invert over the 

 sponge a funnel, passing the cord through it; suspend 

 by the cord and keep the sponge moist by pouring 

 water through the funnel tube; the funnel prevents 

 the sponge from drying too rapidly. Observe the seeds 

 sprout and produce plants growing upside down. 

 What can be inferred ? Does gravity or moisture 



