78 



BOTANY. 



the contrary, they are always ahsorlbed in the condition of 

 compounds, as water, carhon dioxide, and the 



Nitrates 



Sulphates 



Carbonates 



Phosphates 



Silicates, or 



Chlorides 



of 



Ammonia. 

 Potash. 

 Lime. 

 Iron. 

 Soda, or 

 _ Magnesia. 



Of the last the nitrates of potash' and ammonia, sulphate 

 of lime, carbonates of ammonia and lime, are probably to 

 be considered as the most important for ordinary plants. 

 Water is necessary for all plants, and carbon dioxide for 

 those which are green. 



149. In addition to the foregoing many organic com- 

 pounds are absorbed in particular cases, as in those plants 

 which live in decaying animal or vegetable matter (sapro- 

 phytes), as well as those which absorb the juices from liv- 



