CHAPTER II. 



WHAT THE ROOT, STEM, AND LEAVES HAVE TO DO. 



1. The plant fades. Why? Experiment shows that it is because 



water is withheld. 



2. The root an absorbing organ. 



3. Water is exhaled from the leaves. Transpiration. Absorption. 



4. Other substances, besides water, are absorbed. The ash, and inor- 



ganic constituents of plants. 



5. The organic compounds of carbon, oxygen, hydrogen, and nitrogen. 



6. Ternary and quaternary compounds of these elements are in 



contrast. 



7. Source of carbon in carbonic acid. 



8. Liberation of oxygen by plants under the influence of sunlight. 



Assimilation. 



9. Source of nitrogen. 



10. Processes of absorption, transpiration, assimilation, and respiration, 

 performed by " organs of nutrition," viz. the root, stem, and 

 leaves. 



I. By this time the weed which you gathered has pro- 

 bably faded ; the leaves, now become soft and flaccid, 

 are drooping, and the stem has lost much of its stiffness. 

 How is this? 



If the specimen be not quite withered, plant it again in 

 the soil, and cover it with a flower-pot ; or better and more 

 easily done, put the root in water, and place the whole in a 

 cool, shaded place for a few hours. We shall anticipate 



c 



