CON T E N T S. 



Page. 



< icneral remarks on the mineral constituents found in organisms 9 



Historical notes 9 



Mineral compounds found in organisms 12 



Variety of functions of mineral substances 13 



General value of certain mineral salts 14 



The low atomic weight of the mineral nutrients 15 



The physiological role of phosphoric, acid 16 



Relation of phosphoric acid to proteids and to the division of cells 16 



The physiological importance of lecithin 17 



Phosphoric acid in chlorophyll 19 



Potassium phosphate as a cell constituent 19 



The physii (logical role of silica 20 



The physiological role of iron compounds 21 



Relation between the coloring matter of the blo< id and < if the leaf 21 



Influence of iron and other mineral nutrients on the formation of chloro- 

 phyll 21 



Fertilizing effect of iron salts 22 



Organic compounds containing iron 22 



Iron in fungi 23 



Manganese in plants 23 



The physiological role of halogen compounds 24 



Plants raised without chlorids 24 



Value of potassium chlorid for buckwheat 24 



Beneficial and injurious action of chlorids 25 



Absorption of chlorids by aquatic plants 26 



Sodium chlorid in animals 26 



Fluorids in physiological relations 26 



Behavior of plants to potassium bromid .. 27 



Relations of organisms to iodin compounds 27 



The physiological role of alkali salts 28 



Importance of potassium for the formation of starch and protein 28 



Beneficial action of s< idium salts upon plants ."«0 



Necessity of sodium salts for animals 30 



Can potassium salts be replaced by rubidium salts in green plants and in 



animals? _ 31 



Behavior of fungi toward rubidium salts 33 



Physiological superiority of potassium salts 34 



The physiological role of calcium and magnesium salts 35 



Distribution of lime and magnesia in plants 35 



The physiological importance of lime salts in plants 38 



Views on the functions of lime salts 41 



Formation of lime incrustations 46 



Can calcium in plant cells be replaced by strontium? 46 



i 



