CONTENTS XL 



CHAPTER IV 

 Chemical Changes During Germination 



PAOB 



34. Conversion of Starch to Sugar . . . '55 



Photo-synthesis. 



35. Plant Catalase ...... 56 



SECTION II.— SOILS 



CHAPTER V 

 Proximate Constituents of Soils 



Limestone^ Humus^ Sand^ and Clay. 



36. Limestone ....... 57 



37. Humus . . . • . . .59 



38. Sand ....... 60 



39. Clay ....... 61 



Plant Nutrients in the Soil. 



40. Phosphoric Acid, Potash and Nitrates . . .62 



CHAPTER VI 

 Chemical Properties of Soil 



Nitrification. 



41. Nitrification of Ammonium Compounds . . .65 



42. Effect of Acidity ...... 66 



43. General Occurrence of Nitrifying Bacteria . . 66 



Denitrification. 



44. Measurement of Denitrification .... 66 



Ammonification. 



45. Measurement of Ammonification . . . . 67 



