256 BIOLOGY. 



systems, sun and planet, air and water with earth, light 

 and matter, electrism and chemism. 



1361. The functions divide into those of the (Ether- 

 organs blossom, and the planetary organs stem. 



I. FUNCTIONS OF THE TRUNK. 



1362. The functions of the trunk are those of the 

 tissues, systems and members ; thus first of the cells, 

 vessels or ducts and tracheae ; secondly, of the bark, liber 

 and wood ; lastly, of the root, stalk and foliage. 



1. Facts. 



1363. The phenomena to be regarded in plants bear 

 relation to their constituent parts, and the changes or 

 preliminary incidents which they undergo. 



A. Constituent Parts. 



The chemical constituent parts of vegetables are inor- 

 ganic and organic. 



i 



a. INORGANIC BODIES. 



Elements. 



1364. The plant contains all the primitive bodies; 

 carbon, oxygen, hydrogen and nitrogen. The carbon 

 forms the principal mass, and almost alone constitutes its 

 solid parts. The nitrogen is only present in small quan- 

 tity, being, as it were, a trace only of the future animal 

 kingdom. 



1365. In the plant all the elements are also active, as 

 the aether, which, through the gravitation of the root, 

 strives towards the middle point or centre of the earth. 

 The light, which imparts the general polarity and decom- 

 position, as well as produces colours. The latter appear 

 to reside in the starch-flour. The heat, that sustains the 

 indifference, promotes the evaporation and the course of 

 the sap, as also protects the plant from being killed by 

 frost or cold. The air that penetrates through the spiral 

 vessels to all parts, and is also met with occasionally in 



