268 BIOLOGY. 



1423. The greatest amount of induration must origi- 

 nate in the body of the spiral vessel, because in it the 

 process of oxydation takes place in the most active man- 

 ner. From the same cause the process of nutrition must 

 also be supported by it in the most powerful manner. 

 The wood is the chief seat of nutrition. 



c. Tracheal-process Oxydation. 



1424. The structure of the spiral vessels, their resem- 

 blance to the tracheae or air-tubes of insects, their distri- 

 bution throughout the whole trunk, the air they contain 

 which is found decidedly free in the plant, leave no 

 doubt that the tracheae are air-conveying organs, and 

 consequently have, like the arteries in animals, the pro- 

 cess of respiration directly intrusted to them. 



1425. Now through the process of respiration the 

 general polarity, and consequently the cause or funda- 

 mental principle of all life, enters the plant. 



1426. The tracheae penetrate or traverse the whole 

 plant from the apex of the root to that of the flower. 

 Their operation must therefore also extend through the 

 whole plant. 



1427. The tracheal system must also govern the plant 

 by polarity, and thus in an immaterial manner. 



1428. This polarity acts simply in the direction of 

 the plant's longitude, not transversely, like the material 

 fundamental processes. 



1429. The tracheae impart in a spiritual manner the 

 antagonism between the root and fabric of the stem. 



1430. As the tracheae are, or constitute, the highest 

 system of the plant, so must it be them upon which the 

 light principally acts. The material processes of plants 

 are kept in activity by the antagonism of light. 



1431. By this only are the instantaneous changes, 

 which follow upon the influence of light or section of the 

 spiral vessels, to be explained. Upon this, therefore, 

 depends the instantaneous elevation of the processes 

 under the influence of a ray of light, and their depres- 

 sion, if only a cloud pass in front of and obscure the 



