114 BIOLOGY. [BOOK 11. 



we may employ this word in speaking of blind organic finality) 

 it was destined to be burned by the beet-root itself during the 

 second year of vegetation, when florescence and fructification are 

 developing themselves. 



However this may be, the nutritive substances, when suf- 

 ficiently elaborated, are assimilated ; that is to say, their molecules 

 intercalate themselves between the organic molecules already 

 formed, either to replace those which have been destroyed, or to< 

 bring about the enlargement of the cell ; others spontaneously 

 organize themselves in the blastemas. 



We may form some probable conjectures as to the special office 

 of the various categories of organic substances. It is probable 

 that the hydrates of carbon and the fatty bodies are especially 

 transformed into cellular membranes^ these membranes being prin- 

 cipally constituted of cellulose, the molecule of which is almost 

 indentical with that of starches, sugars, and fats. Thence come 

 also without doubt the vegetal acids, tannin, and the colouring 

 matters. 



The proteic substances are probably employed in the formation 

 of internal azotized utricles included in the cells, and of the 

 cellular protoplasm and the chlorophyllian particles. 



They also furnish, but by incomplete oxydation, by degradation, 

 asparagin, of which we have spoken, and without doubt the 

 vegetal alkaloids (quinine, morphine, strychnine, &c.), quaternary 

 but not proteic substances, and of which the molecule, very 

 complex, very rich in carbon, and tolerably rich in hydrogen, 

 contains also a notable proportion of oxygen and very little 

 azote. 



2. Inorganic Substances. 



Besides atmospheric gases, a number of mineral substances are 

 introduced into the plant through the roots. The principal are 

 alkaline and terreous bases : potash, soda, ammonia, magnesia, 

 lime, generally salified by sulphuric, azotic, phosphoric, silicious 

 and carbonic acids. Many of these substances do not contribute 



