CONTENTS OF PART 



LECTURE VI. 



SUBSTANCES OF "WHICH PLANTS CHIJEFLY CONSIST. 



Woody fibre or lignin— its constitution 



and properties p. 103 



Starch — its constitution and properties. . . .106 



Gum — its constitution and properties 108 



Of Sugar— its varieties and cliemical con- 

 stitution 109 



Mutual relations of woody fibre, starch, 



gum, and sugar Ill 



Mutual transformations of woody fibre, 

 starch, gum, and sugar 112 



Of the fermentation of starch and sugar, 

 and of the relative circumstances under 

 which cane and grape sugars generally 

 occur in nature p. 115 



Of substances which contain nitrogen. — 

 Gluten, vegetable albumen, and diastase. 116 



Vegetable Acids. — Acetic acid, oxalic acid, 

 tartaric acid, citric acid, malic acid 121 



General :>bservations nn the substances 

 of which plants chiefly consist 126 



LECTURE VIL 



CHEMICAL CHANGES BY WHICH THE SUBSTANCES OF WHICH PLANTS CHIEFLY 

 CONSIST ARE FORMED FROM THOSE ON WHICH THEY LIVE. 



Chemical changes which take place du- 

 ring germination, and during the devel- 

 opement of the first leaves and roots,. . . 130 



Of the chemical changes from the for- 

 mation of the true leaf to the expansion 

 of the flower 134 



On the production of oxalic acid in the 

 leaves and stems of plants 137 



Of the chemical changes between the 

 opening of the flower and the ripening 

 of the fruit or seed ^ 13© 



Of the chemical changes which take place 

 after the ripening of the fruit and seed . . 143 



Of the rapidity with which these changes 

 take place, and the circumstances by 

 which they are promoted b. 



LECTURE VIII. 



HOW THE SUPPLY OF FOOD FOR PLANTS IS KEPT UP IN THE GENERAL 

 VEGETATION OF THE GLOBE. 



Of the supply of ammonia to plants 156 



Of the supply of nitric acid to plants 159 



Theory of the action of nitric acid and 



ammonia 163 



Comparative influence of nitric acid and 



of ammonia in different climates 166 



Stimulating influence of these compound* t). 

 Concluding observations regarding the 



c rganic constituents of pl.-uiia 168 



Of the proportion of their carbon which 

 plants derive from the atmosphere 145 



Of the relation which the quantity of car- 

 bon extracted by plants from the air, 

 bears to the whole quantity contained 

 in the atmosphere 147 



How the supply of carbonic acid in the 

 atmosphere is renewed and regulated .. 148 

 eneral conclusions in relation thereto. .. 156 



