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Even in the cryptogamia, where no flowers are 

 distinct, still there is every reason to believe that the 

 production of the seed is effected in the same way as 

 in the more perfect plants. The mosses and lichens, 

 which belong to this family, have no distinct leaves, 

 or roots, but they are furnished with filaments which 

 perform the same functions ; and even in the fungus 

 and the mushroom there is a system for the absorp- 

 tion and aeration of the sap. 



It was stated in the last lecture, that all the differ- 

 ent parts of plants are capable of being decomposed 

 into a few elements. Their uses as food, or for the 

 purposes of the arts, depend upon compound arrange- 

 ments of those elements which are capable of being 

 produced either from their organized parts, or from 

 the juices they contain ; and the examination of the 

 nature of these substances, is an essential part of Agri- 

 cultural Chemistry. 



Oils are expressed from the fruits of many 

 plants ; resinous fluids exude from the wood ; sac- 

 charine matters are afforded by the sap ; and dyeing 

 materials are furnished by leaves, or the petals of 

 flowers : but particular processes are necessary to se- 

 parate the different compound vegetable substances 

 from each other, such as maceration, infusion or diges- 

 tion in water, or in spirits of wine : but the application 

 and the nature of these processes will be better under- 

 stood when the chemical nature of the substances is 

 known ; the consideration of them will therefore be 

 reserved for another place in this Lecture. 



