WOOD'S CLASS-BOOK OP BOTANY. ill 



819. When does the former phase become visible ? When the latter f 



820. Explain the phenomena of blanched plants. 



821. Describe the interesting experiment of Saussure. 



822. Why is no oxygen obtained when boiled or distilled water is used ? 



824. What are the results of transpiration and respiration on the sap ? 



825. What proportion of carbonic acid in the air ? Whence is it derived ? 



How much is added to the atmosphere annually ? 



826. Why does the carbonic acid not accumulate in the air? 



827. How might the air become poisonous for animals? 



828. Now show how the animal and vegetable kingdoms mutually aid 



each other. 



CHAPTER VII. 



829. Name the four organogens, i. e., organic elements. 



830. In what proportion does each exist ? In what proportion all? 

 What the per cent, of carbon ? What gives solidity and strength ? 



831. What do the oxygen and hydrogen formin plants ? 

 Give some examples of its quantity from the table. 



832. Name some earthy elements found in plants. 



833. Give from the table some examples of the proportion of ashes and other 



elements in vegetables. 



834. What is the object of inquiry in Agricultural Chemistry ? 



834. What is the food of plants? Whence comes their nourishment? 



Whence their carbon ? Their oxygen ? Hydrogen ? Nitrogen? 



835. What the whole quantity of carbon in the air ? 



837. Of what does soil consist ? Its organic materials. 



838. Of what is water composed ? Whence the ammonia in rain ? 



839. What is the composition of ammonia ? 



840. What source of nitric acid in the air ? 



841. What are air-plants ? Give some examples. 



842. Name three requisite conditions of healthy vegetation. 



843. What of the supply of the first ? Of the second? 



844. What is the object of tillage ? What of sub-soiling ? 



845. What the object of manuring ? What the use of amendments f 



846. What is the good of bone-manure ? What of guano ? 



848. What is fallow ground? What its benefit ? 



849. What gives efficiency to all these materials ? 



850. Can you here state the outlines of digestion ? 



851. What are the constituents of the proper juice ? 



852. From this vital fluid what is first formed ? Next ? Thirdly ? 



853. Where are gum, starch, and sugar deposited ? 



854. How does sugar differ in composition from starch ? 



855. How may starch become cellulose ? How become sugar ? 



856. Can you distinguish the vegetable products into two classes ? 



857. On what principle is the table constructed ? Illustrate. 



PART THIRD. 

 CHAPTER I. 



858. What is the object and aim of Systematic Botany ? 

 860. What is the higher purpose accomplished by it? 



