122 GENERAL FLUID COMPONENTS. [LECT. III. 



formed in the soil, in a state of division sufficiently 

 minute to be suspended in water, and drunk in by 

 the absorbent vessels of the roots. This is in some 

 degree proved by the effect of change of situation 

 on plants which naturally grow near the sea. 

 Most of these plants, when burned, yield soda ; 

 but, when they are removed from the sea-shore, 

 and cultivated in an inland situation, potash in- 

 stead of soda is procured from their ashes. 



As the sap undergoes the same exposure to the 

 air and light in all plants, and one product only 

 can be formed in each plant by this exposure, the 

 difference of the proper juice in different plants, is 

 a strong argument in favour of the existence of 

 vegetable glands, independent of the undeniable 

 proof afforded by the formation of the very dif- 

 ferent products, which are deposited in different 

 parts of the same plant. Unless there were glan- 

 dular organs, one product only could be produced 

 in each plant by the function of the leaves, and the 

 action of light and of air on the sap. The secre- 

 tions of plants formed from the proper juice are 

 very numerous, and known under the names of 

 gum, fecula or starch, sugar, gluten, albumen, 

 gelatin, caoutchouc, wax, Jixed oil, volatile oil, 

 camphor, resin, gum resin, balsam, extract, tan- 

 nin, acids, aroma, the bitter, the acrid and the 

 narcotic principles, and ligneous Jibre. These are 

 found in different parts of plants without any uni- 



